URBAN MORPHOLOGICAL THEORY AND SPATIAL DIFFERENTIATION
IN A CARIBBEAN CITY: RESIDENTIAL LAND USE FROM 1948 TO
1975 IN SANTO DOMINGO, THE DOMINICAN REPUBLIC
HOWARD McKAY TUPPER
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
I have had innumerable occasions over the past years to be grate-
ful to many persons whose encouragement, patience, confidence, and
expert assistance have made this research possible. My decision to
become a geographer was invited and supported by Dr. Clark Cross. The
intensely rewarding classroom experiences created by Dr. James R.
Anderson and his dedication to the geography profession have been in-
spiring. There have been other educators with whom I have had the
pleasure of studying. Dr. John Saunders taught me demographic prin-
ciples; Mr. Carl Feiss guided the preparation in urban studies.
I greatly appreciate their dedication to their profession.
Others whose academic excellence I admire have also been my
friends, helping me to overcome obstacles to and enjoy the rewards of
academic life. Probably none has been more patient and helpful and con-
cerned for my welfare than Dr. Gustavo A. Antonini. May the wind never
fail, and the sea remain gentle. Dr. Katherine Carter Ewel has been a
sympathetic friend whose intellect and insight are well known to her
friends and associates. And, I am thankful for the gracious goodwill
of Drs. Robert Marcus and Earl Starnes.
It is appropriate to mention two university programs that have
contributed so much to my education. The Center for Latin American
Studies' demography program generously supported both my training as a
population geographer and my residency in the Dominican Republic. The
Department of Geography teaching assistantship provided invaluable class-
room experience for which I am deeply grateful. The interaction shared
with the department faculty, staff, and students has given me many
There are those individuals whose skills become invaluable in the
preparation of such a study. Mr. Jos3 J. Hungrfa was a wonderful
Dominican host who extended a generous welcome that included the re-
sources of the Geographic Institute. I extend my sincere appreciation
to Sue Kirkpatrick for her typing and editorial skills so important to
the preparation of this dissertation.
To John, Christine, and Earnest who have wanted only the best for
me, I thank you and am happy that you share the pleasure that comes with
the'attainment of this goal in our lives and the expectations of the
TABLE OF CONTENTS
ACKNOWLEDGMENTS .. ......
ABSTRACT . . . ... . . vi
ONE INTRODUCTION .. . . . .. 1
Purpose of Study .
Research Objectives .
The Study Plan .
TWO THE STUDY AREA .........
The Dominican Republic .. ........
Santo Domingo City . . . .
Recent Urbanization . . .
The Housing Problem .......
THREE URBAN SOCIAL DIFFERENTIATION .....
Concentric Zone Model
The Applicability of the
Caribbean . .
Sector Model . .
The Applicability of the
Multiple Nuclei Model .
The Applicability of the
Caribbean . .
Sector Model to
Model to the
Model to the
FOUR IDENTIFYING LAND USES AND HOUSING CONDITIONS ..
Aerial Photography Data Base .. .... .. .. .
Temporal and Spatial Framework . .
Mapping Criteria ....
Aerial Photography Interpretation .. ......
Field Survey ...........
Residential Land Use Definition of the Field Sample .
. . . .
. . . . .
FIVE TESTING URBAN ECOLOGICAL THEORY . . .... .84
Allocating Zone and Sector Location . ... 84
Testing the Models of Land Use Change ...... 90
Testing the Models for 1948 Residential Land Use 97
Factor Analysis . . . ... .104
SIX LAND USE CHANGE . . . .... 115
1948 Land Use ... . . . 115
1974 Land Use ................... 123
Land Use Change, 1948-1974 . . .. 127
SEVEN RELATIONSHIPS AMONG LAND USE CHANGE, HOUSING, AND POPU-
LATION . . . ... 140
Evolutionary Theory of Urban Change . ... 140
Housing Conditions . . . . 143
Population Estimates . . . 145
Housing Typology . . . . 149
EIGHT SUMMARY AND CONCLUSIONS . . . .. 157
REFERENCES . . . . ... .. ..... 165
BIOGRAPHICAL SKETCH . . . .. 178
Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy
URBAN MORPHOLOGICAL THEORY AND SPATIAL DIFFERENTIATION
IN A CARIBBEAN CITY: RESIDENTIAL LAND USE FROM 1948 TO
1975 IN SANTO DOMINGO, THE DOMINICAN REPUBLIC
Howard McKay Tupper
Chairman: Gustavo A. Antonini
Major Department: Geography
Land use change, specifically the spatial patterning of residen-
tial land use change, in the capital city of the Dominican Republic was
examined over a 27-year period when both the nation and city underwent
many important changes, including urbanization. The principal objective
of this study is to assess the usefulness of urban morphological theory
to explain the growth of Santo Domingo. Associated objectives include
the identification of trends in the urban change and alternatives for
development over the remaining decades of the century.
The research methodology employed three data bases. Both 1948
and 1974 aerial photographic coverage of the city provided information
for a five-category land use classification system, and the results of
the interpretation were mapped in units of one hectare. Final maps are
scaled at 1:80,000. The third data base was a 10-percent sample of all
streets in which land uses were determined in a block-by-block canvass
that included sampling for 40 variables measuring lot and structure
The data bases were merged by the location of each hectare of
urban land included in the city. Zone and sector models were tested to
assess whether they were useful in explaining the spatial differentia-
tion over the study period. The 45 variables describing urban land
use in both 1948 and 1975 were factor analyzed to discriminate among
low-, medium-, and high-income residential land uses.
The city, entering the early stage of industrialization accom-
panied by extensive urbanization, exhibits a sectoral pattern of land
use change. The single example of a zone was found for high-income
residential land that had aggregated at what had been the urban fringe
about 1948, before the inception of the present phase of modernization.
A general absence of filtering, little suburbanization, and extensive
marginal housing at the city's edge are evidence that this Caribbean
capital departs from the morphological patterns identified for Anglo-
American cities of comparable size and importance.
Purpose of Study
Contemporary urban theory explaining the area differentiation of
the city can be organized according to social systems, group decisions,
and habitat. First, there is the theory which relates to the system of
social organization at the local community level and involves the
social structure and associated institutions that constitute the urban
environment. Second, there is the theory of behavior of city dwellers
expressed in attitudes and ideas and manifested in decisions affecting
urban development. Third, there is the urban habitat.in its more inclu-
sive sense of people, technology, resources, and interrelationships.
The latter is the concern of human ecologists and urban geographers.
These geographers as well as urban ecologists are specialists in the
physical expressions of social systems, group decisions, and habitat
that are termed urban morphology. This study is concerned with the for-
mal, or structural, city that is included in residential land use and
which is assumed to be representative of the ecological relationships
among urban systems.
Accumulating urban morphological theory is based upon wide-
ranging conditions encompassing urban experiences in different cultures.
However, a majority of published research reflects a Western, developed
society orientation, and there is the possibility that the theoretical
constructs may not apply to developing economies which are not yet as
fully modernized nor capitalistic.
Research into the urban milieu of other regions could be useful
for testing the validity and reliability of urban theory drawn from
Anglo-American and Western European cities. Urban morphological study
of Caribbean cities, modest by comparison with that accomplished else-
where in the Western Hemisphere, is insufficient to conclude that the
hypotheses advanced for urban change are applicable to such rapidly
modernizing cities as Kingston, Havana, or Santo Domingo.
If modernization in these Caribbean cities departs from the pro-
cess identified in the United States, then these capitals may evolve
spatial configurations distinct from Anglo-American cities. The impli-
cations for urban growth planning are important, especially for those
officials who are concerned with efficient utilization of scarce re-
sources. Research of Caribbean urban geography has the potential of
contributing additional, valuable information expanding our knowledge of
the processes of urban change. Dwyer (1975, 248) has said,
What is needed is more extensive investigation into the Third
World city in such disciplines as geography, sociology, social
anthropology and psychology in order to evaluate further the
economic, social, cultural and other forces at work in shaping
patterns of urban development. Existing knowledge of the
urbanization process in the nature of housing problems in
particular is all too often either ignored or badly applied.
Santo Domingo, capital city of the Dominican Republic, is a
rapidly urbanizing city that is undergoing modernization. Because of
its importance both as a regional and national center, Santo Domingo
has required a proportionally larger share of the nation's resources
than other Dominican cities. Because of its more rapid population
growth, the capital will require an even larger share in the immediate
This study is directed specifically at identifying base-line
conditions in Santo Domingo of land use and housing which must be evalu-
ated in formulating a comprehensive housing program. "Housing clearly
reflects the economic and demographic structure of a society-its level
of development, the distribution of its income, the rate of population
growth, and the pace of expansion" (Gilbert and Ward 1978, 285). This
study of residential land use change will identify conditions in intra-
urban form under the tacit assumption that housing is indicative of
socioeconomic classes and that there is a reasonably clear relationship
between social structure and housing.
There is a need for systematic investigation of housing grouped
to explain urban structure and social area differentiation (Herbert 1973,
124-127). Recent quantitative studies generally have ignored residen-
tial structure and land use in modernizing societies.
This study of Santo Domingo is an effort to uncover cross-
cultural urban ecological conditions explained by general theory of
urban change including three models of land use change. These models
include concentric zones, sectors, and multiple nuclei. Santo
Domingo was selected as representative of the urban environment in a
Caribbean setting. It is undergoing modernization in a region experi-
encing much change that may be best understood within the context of
The complexity of urban conditions restricts the scope of any
analysis of the mechanisms and the social organization which accompany
change. But land use study is a necessary step in developing a compre-
hensive understanding of conditions in the city. Residential land use,
specifically housing in its physical and social connotations, repre-
sents the largest area of the city, the majority of all structures, and
the greatest portion of the metropolitan population, and involves a
great many of the daily activities of city dwellers.
This research is focused on land use change in Santo Domingo over
the 1948-1975 period. Included in the land uses were three residential
categories representative of socioeconomic status; another category of
other land use that was an aggregation of public, commercial, and in-
dustrial uses; and a fifth use of open, undeveloped land. The research
involved the analysis of several data bases in order to address a num-
ber of timely, important questions.
There were four major goals of the study. Each included a number
of specific questions relating to land use and housing within the con-
text of urban ecological conditions. These four objectives are
1. To determine the extent of modernization Santo Domingo sus-
tained over more than one-quarter century. Specific objectives included
(a) determining whether modernization had transformed the traditional
morphology of the city; (c) determining whether land uses were becom-
ing more homogeneous; (d) determining whether growth of residential land
use was concentrating, and, if so, whether this occurred along the
transportation corridors; (e) determining whether there was evidence
that density of land use was increasing and that a gradient of land use
existed; (f) determining whether there was an evolutionary sequence to
growth which included evidence of decentralization.
2. To determine which of the ecological models of urban change
was (were) best in explaining land use patterns. Specific objectives
included (a) determining the direction of change; (b) determining
whether there was evidence of a housing cycle that incorporated filter-
ing, the shift in the use of housing from higher to lower socioeconomic
levels of the occupants.
3. To identify housing according to socioeconomic level. Spe-
cific objectives included (a) determining whether the field survey of
housing could predict land use as identified from aerial photography;
(b) ascertaining whether housing aggregated by ecological divisions in
land use change models.
4. To isolate those aspects of the urban condition in Santo
Domingo which would assist in planning for the future of the city.
Specific objectives included (a) determining the likely trends in the
immediate growth of the city; (b) identifying desirable alternatives
to expected urban change; (c) recommending possible means for achiev-
ing desired alternatives to growth patterns identified for the city's
The Study Plan
There were three data bases incorporated into the study of land
use and housing in Santo Domingo. Aerial photographic coverage, accumu-
lating since 1916, was examined at the Geographic Institute of the
Autonomous Univeristy of Santo Domingo, and two flights were selected
which were representative of the city's condition, one prior to the
latest transformation from a traditional to modern capital. The 1974
coverage was the most recent available and provided up-to-date informa-
tion about the extent of modernization.
The photographs were interpreted during 1979-1980 at the Carto-
graphic Laboratory of the University of Florida's Center for Latin
American Studies. The 1974 photography was interpreted first, and land
use was grouped into three residential categories according to socio-
economic indicators of low-, medium-,and high-income housing. The land
use information was transferred to a land use map scaled at 1:12,500.
A grid of one-hectare cells was overlaid on the land use map in order
to aggregate the predominant use into hectare-sized blocks that would be
comparable with the 1948 conditions as well as the field survey results.
Thus, the largest proportion of any land use determined the classifica-
tion for the hectare cell. The coordinates of longitude and latitude
for each cell were used to store the land use information for the later
analysis that was to include both comparison with 1948 aerial photog-
raphy and the 1975 field sample of city streets.
The photography for 1948 was interpreted in like manner. A land
use map, scaled at 1:12,500 was produced, and the information, aggre-
gated into hectare-sized cells, was stored according to the geographic
location in the same grid system as used for the 1974 base year.
In 1975, a survey of approximately 10 percent of the nearly
1,400 streets was conducted in order to collect information about hous-
ing in Santo Domingo. The entire length of each randomly selected
street was traversed. Field information concerning 40 variables relat-
ing to socioeconomic level of residents, the building materials used
in construction, general state of repair of structures, number of
floors, and extent of infrastructural services was collected, as well
as data about other land uses and nonresidential structures also found
along the street. Over 9,100 structures were included in the sample.
They were located as sites on a map of the city which included the
same hectare-sized system of cells used for location of the remotely
sensed data. One-half of the sites found in each sample hectare were
randomly selected and stored for analysis.
From the aerial photographs, five land use maps for each of the
two years were completed which displayed the individual land use cate-
gories and which became the bases for comparative analysis. The merge
of the computer-stored data produced land use change information aggre-
gated by hectare cells which were mapped to display the 1974 land uses
of all 1948 hectares which had changed use during the intervening years.
In order to test the applicability of the zone and sector models
as explanations of the land use change patterns, the models' geometric
configurations were superimposed upon the 1974 and 1948 land use maps.
Each hectare cell of land was given a value for its location in both
a zone and sector. Variations from the expected frequencies of land
use in each zone and sector were tested for significant differences.
The field survey of structures included 747 hectares of the city's
area in 1974-1975. Only 44 percent of the survey area was found to be
exclusively residential. Of 520 hectares found to contain some propor-
tion of residential structures in both the survey and 1974 aerial
photography, 333 were entirely developed in housing. It was nec-
essary to arrive at some criterion for designating the remaining hec-
tares as either residential or nonresidential in order to relate the
housing information to land use and land use change over the 27-year
period. All proportions of residential to nonresidential structures
per hectare were considered in relation to the loss of information
that would occur under various land use mixes. The 50-percent cri-
terion was chosen after careful analysis.
Once the minimum proportion of residential structures allowable
in any hectare cell designated residential was arrived at, the survey
data were merged with the remotely sensed data bases by cells of resi-
dential land use in order to estimate housing conditions throughout
the city during the 1974-1975 period. The field variables relating to
housing and neighborhood conditions were augmented with others which
included the land use change model configurations and the distance of
each hectare to the city center. To reduce the housing information to
.a few indicators of socioeconomic levels of residential land use, the
data were factor analyzed. Four factors were produced, three of which
discriminated among the field variables relating to socioeconomic
THE STUDY AREA
The Dominican Republic
The Dominican Republic is the larger of the two nations sharing
the island of Hispaiola in the Caribbean archipelago. Its long Spanish
heritage began with the founding of the first permanent European settle-
ment in the New World at what is now the capital city of Santo Domingo.
Culture and language continue to bind Dominicans to their Latin American
cousins and the Spanish mother country. But four hundred years of in-
sularity, demographic and economic stagnation resulting from Spanish
colonial indifference, and numerous foreign incursions have contributed
to the evolution of a provincial, traditional island society which
shares a Caribbean culture based on similar history, ethnicity, politics,
and economy. Ruled by a small elite of ranching families who were
neither wealthy nor a landed aristocracy so typical in Latin America,
the republic was two centuries later than the rest of the Spanish-
speaking New World in experiencing the concentration of riches and
power in a Dominican aristocracy (Bell 1981, 111-116).
The Dominican oligarchy is comprised of a few families of colonial
Spanish heritage and a small number of wealthy Dominican families who
became successful under the long Trujillo era from 1930 to 1961 and
managed to retain their influence and continue to share power. In
1960, Bosch (1978, 266) described this class as including politicians,
bankers, industrialists, wholesalers, doctors, lawyers, merchants, land-
owners, military officers, prelates, and intellectuals.
The Dominican Republic can be described as a social democracy com-
mitted to private ownership of property and free enterprise. Although
the government has been antisocialistic, the extensive holdings of the
Trujillo family that were expropriated after the dictator's assassina-
tion in 1961 remain to a large extent in the public sector.
The island nation's economy is primarily agricultural. A warm,
moist climate influenced by the Trade Winds coupled with a relatively
large expanse of arable land, especially the rich Cibao Valley of the
Yaque del Norte River, have sustained the traditional cash cropping of
sugarcane, coffee,and tobacco, while substantial harvests of food crops
including rice, beans, peas, and fruits are grown on the many small
holdings found throughout the nation. Even the industrialization is
tied to the agricultural base, for sugar growing and processing employ
about 54 percent of all industrial labor (Repdblica Dominicana 1977, 4).
Relatively rich in natural resources in comparison with the other
Caribbean nations, the Dominican Republic has a large labor supply as
well, but does not enjoy sufficient capital to pursue a massive national
development program simultaneously incorporating improvements in all
sectors of the economy. Between 1966 and 1972, total national expendi-
tures averaged RD$ 249.01 million with social and economic portions
about equal in the national budget (Table 2-1).
General economic conditions include the need to increase agricul-
tural production and the food-processing industries that help feed a
rapidly increasing population. But such economic expansion is impeded
CND~Lf LCNt 'D(~' .-.lra 'DL -OO flm
DL- 0Nt L
-. r~cto-a 0.- cCC. ~~O '0 DOII
--~ a- a~'L t~m -- t On
Cc~t C~- -t (~r .(0 a 00L DO
to OLSLO CD 0- .- -.OOC 0-O -.~t I
tO 0(000 CoO a-oL OH~OL 0O ttO 0.~ C
to oo oo o~ cooo,-, ~o; ,
1- -at,,,-..- O0La a a
Laa .- LD~t Cart. -m D LNo ~ o~
a am~ a ~ Dnn Dl-t 5m t.. Otoan tC ...
aaa` aO Do.D L a DC, t
to ~ 04to- C h C C..t 10 C NCD CC
it do~n,~I ~~ ~
by the loss of capital from the profits expatriated by extranational
corporations. There is the loss of valuable foreign exchange expended
to purchase foodstuffs that might have been grown at home had more land
and capital been invested in food staples rather than cash crops. The
high prices that are charged for the fuel that the republic must import
deprive the economy of badly needed revenue.
Probably about one-half of all Dominicans now reside in cities.
Although the provincial capitals draw many rural poor, still the largest
numbers of migrants are found in Santiago and Santo Domingo (Figure 2-1).
It can be estimated that 20 percent of all Dominicans live in the capi-
Santo Domingo City
Founded about 1502 along the Caribbean coast at the mouth of the
Ozama River, Santo Domingo was established as the colonial communication
link and base for Spain to explore the New World. The island is in the
hurricane track; the town was moved from its original site on the east
bank of the river to the present position after a hurricane destroyed it
shortly after its founding. Even as recent as 1930, Santo Domingo was
destroyed by another tropical storm.
The entire city (Figure 2-2) is in relatively homogeneous terrain.
The immediate geologic structure is porous, well-drained, soft calcareous
and very hard, coraliferous limestone rocks arranged in relatively flat
terraces which parallel the sharply sculpted coastline. Kilometer-wide,
nearly level ledges rise to about 70 meters elevation in the west, about
40 meters in the east.
The Ozama River joins with the Isabela River at the northeast
limit of the city. These rivers drain a broad watershed which incor-
porates an agricultural interior largely cultivated in sugarcane. They
have cut deep channels in the hard limestone substrata. Three bridges
in the city crossed these in 1975, one spanning the Isabela River, and
the other two connecting the eastern part of the city to the main com-
mercial, industrial, recreational, cultural, and residential city.
There are a few narrow marshlands along the floodplain which disappears
in places along the Ozama as it flows through the city to the Caribbean.
The western part of Santo Domingo is built upon a flat peninsula
between these two rivers and the Haina River. In the northwest, the
land is dissected by steeply sloping stream beds that have created a
relatively hilly terrain. Until recently, land here had been sparsely
settled. High ground has made the cost of providing water mains and
sewers prohibitively expensive,and local water shortages impede develop-
To the east across the Ozama, the land tends to be flat with
shallow, poor soil and extensive rocky outcroppings that contribute to
an arid, desolate landscape of small trees, shrubs, and grasses.
Actually, most land within the present confines of the city is of poor
quality except for a few areas in both the northeast and northwest
where rural settlements used to exist.
The city's presently developed area is extensive in comparison
with its size prior to World War II. The historic center, as shown in
Figure 2-3, with its colonial structures several floors high and ruined
fortifications, comprises an area of slightly more than one square
kilometer. Included in this nearly five-hundred-year-old city are the
restored castle of Diego Colon, the oldest cathedral and hospital, the
Plaza Coldn, city hall, main post office, and other important struc-
tures. According to the first national census in 1908, the colonial
center contained 45 streets and had 2,862 houses. The focus of the city
was the Plaza Col6n which is linked to the ruin of the city wall at the
main gate, Puenta del Conde, by an avenue of the same name. Unlike
many colonial cities elsewhere that were defensive in function, Santo
Domingo still has some of its original fortifications. Since the wall
foundations remain in place, circumferential streets with radial connec-
tions to the main plaza are not in evidence around the city center. On
the east, the fortifications terminate at the steep bank of the Ozama
where the port wharves have been built. Across the river on hills to
the northeast was the small village of Pajarito and a few homes scat-
tered along the bank (Hazard 1873, 219-223).
President Trujillo took office the same year a hurricane in 1930
demolished the capital and claimed thousands of lives. There were
10,000 families without homes. During the next five years, the govern-
ment and private enterprise rebuilt over 6,000 homes, but one-third of
the storm's victims were without permanent housing (Bonnelly 1960, 40).
By 1950, an additional 23,000 housing units had been constructed, bring-
ing the total stock of housing to 41,161. The deficit in housing was
estimated to be about 1,000 units (Republica Dominicana 1960, 40).
Other major developments in the city included the port develop-
ment project begun in 1935. The Ozama entrance was deepened, a break-
water was constructed at the western side of the river mouth to protect
the inner harbor, and over one and one-half kilometers of wharves and
56,000 square meters of warehouse space needed.
By the beginning of World War II, the city had increased in area
contiguous to the west and north of the colonial center. To commemorate
his silver jubilee in 1955, Trujillo authorized construction of the
international fair project which was built at what was then the western
edge of the city. La Feria cost over RD$ 30 million, a huge sum at a
time when the national budget was about RD$ 120 million, but the
Dominican economy was flourishing. To accommodate the anticipated
thousands of visitors to the exhibition, the government, with U.S. in-
vestment, constructed a major tourist hotel, El Embajador.
The Dominican Republic was relatively late entering the Caribbean
tourism industry. The Jaraqua Hotel had been the first large tourist
hotel, but the stigma of the dictatorship discouraged tourism, and only
three large hotels had been built in the city by 1965, none of which
was kept in good repair (Bell 1981, 339-341).
After order was restored following the civil war in 1965, the
nation has enjoyed nearly two decades of reasonably peaceful, osten-
sibly democratic government. An ambitious project to restore the
colonial center is nearly completed and is encouraging a growing tourist
industry. Many of the centuries-old structures have been returned to
their former magnificence when Santo Domingo was the capital of the New
The city port is now used almost entirely for welcoming the thou-
sands of tourists who arrive by cruise ship. Since 1968 when tourists
numbered 68,500, the flow of visitors has reached half a million,
10 percent of whom travel to the island aboard these ships (Repdblica
Dominicana 1978). Most commercial shipping now unloads and loads at
the port of Haina at the western fringe of the capital. In 1978, the
government authorized the expenditure of RD$ 4.7 million to develop
Haina as the main commercial port.
The old city remains the hub of commercial and social activity.
Many large shops, offices, churches, and businesses share the crowded
space, and the lack of high-rise structures, the narrow streets and traf-
fic congestion, and the noise and dust are inducing some activities to
relocate. With a population that is doubling each decade, this city
that was built to serve 30,000 must now provide for nearly one million
Business, commercial warehousing, and light manufacturing can be
found in newly constructed structures along many avenues, especially
Avenida J. F. Kennedy, the northern extension of Avenida M6ximo G6mez,
along Autopista Duarte and Carretera Sanchez, and in the industrial com-
plex of Herrera. There are over 600 firms scattered over the city, e.g.
Metadom, a scrap metal processing plant established by a Spanish firm at
what was once the edge of the city but which has been surrounded by
residences. There are other industrial concentrations in the neighbor-
hoods of La Fe and Luper6n, and across the Ozama along Carretera Mendoza
in Los Minas (Berg6s 1973, 3-4).
The city's growth has been largely unregulated. Although builders
are encouraged to observe such official regulations as published in the
New York City housing code, the absence of zoning restrictions and a
comprehensive plan for urban development have left the expansion of
Santo Domingo to the designs and whims of the construction industry and
a host of official agencies which have little power to enforce compli-
ance with building codes. It is commonplace to find residences, stores,
professional offices, and even light manufacturing scattered along a
street. A new apartment house of six floors can be built next door to a
middle-income, ranch-style home.
Strip commercial activities can be found throughout the city.
The more notable stretches include the extensive development along
Avenida Duarte, beginning at the downtown market area and extending
along most of its length. Similar strip development is found along
Avenues San Martin, 30 de Marzo, Mdximo G6mex, Sabana Larga, Maria Mon-
tez, and Padre Castellanos.
In the most recently constructed residential areas, commercialism
has been centralized to a large extent. The shopping centers, super-
markets, and public markets accommodate neighborhood shoppers. An
example is the Naco shopping center which services a middle- and high-
income residential community built on land that had been the only inter-
national airport for the nation (Figure 2-4). In 1955, the airport was
moved to Punta Caucedo, 29 kilometers to the east of Santo Domingo.
Aeropuerto de las Amdricas was completed in 1971.
Other widely dispersed commercial enterprises include food stores,
called colmados. They are often managed by their owners and resemble
the Ma-and-Pa corner grocery store in large U.S. cities (Norvell 1969,
105, 108-109). Other domestic shopping can be done at the few central
Produce is trucked into the city primarily to the wholesale dis-
trict adjacent to the public markets, and the storage wholesalers dis-
tribute to the markets and the colmados.
Public and institutional buildings, especially schools and ec-
clesiastical structures, also are dispersed widely. There are concen-
trations in the colonial city where restored buildings are providing the
government with much badly needed space. There are other public com-
plexes at La Feria and at the Huacal (a major government office build-
ing), at the sports stadium, around the national palace and along
Avenida P. Henriquez Urbana, at the Museum of Man and symphony hall
facilities, the universities, and at the intersection of Avenida Luper6n
and Avenida 27 de Febrero.
From 1970 to 1977, the Dominican government spent an average of
RD$ 28 million on roads and bridges, with most construction on projects
in or near the capital. These included a four-lane, divided highway
extension to San Crist6bal, another along the northern part of the city
to connect this by-pass with a fourth bridge crossing the Ozama River,
and the Avenida de las Americas which now extends beyond the airport
to San Pedro de Macoris. The Sanchez bridge has helped to ease traf-
fic congestion at the Ozama River.
Automobile traffic has become a major problem. In 1948, there
were fewer than 1,400 registered automobiles and by 1961, they had
increased to only 6,000 private cars in the entire nation; however,
10 years later, there were over 26,000. In 1975, there were about
49,000 registered automobiles, most operated in the capital city
(Rep6blica Dominicana 1952; Bell 1981, 140).
Several reasons account for this rapid expansion in private auto
ownership. In 1962, President Balaguer decreed the end to the
Trujillo-owned taxi monopoly and conferred ownership of 5,000 city taxis
on their drivers. The operators have had a powerful union which sup-
ported the president during his long administration, and, in exchange,
they received a gasoline subsidy that kept the price of fuel low. Addi-
tionally, most intracity public transportation was relegated to the
taxis called pdblicos which numbered 25,000 in 1977 and provided an in-
formal public service on a fee-for-hire basis along routes selected by
their drivers. Bus registration increased from 316 in 1961 to about
1,860 in 1975, with most of the buses being used in intercity transporta-
tion. The municipal bus service has increased dramatically since
President Guzman expropriated all public transport in 1981, including
the pdblicos which are now rented at reasonable rates to their operators.
The Dominican Republic has a better articulated system of cities
than have Cuba and the non-Spanish-speaking Caribbean nations (Clarke
1974, 225). Yet, much industrial growth between 1968 and 1977 occurred
in either Santo Domingo or Santiago. The industrial Incentive Law was
enacted to encourage "the most rapid and effective industrial promo-
tion of the country's economy with the purpose of obtaining permanent
sources of employment and income for our population and a diversifica-
tion of our national economic base" (Presidential Decree of April 23,
1968). The law allows new industries to be exonerated from 90 percent
of import duties and taxes on raw materials, containers, packing mate-
rials, fuel and lubricants, and 50 percent of net income when re-
invested in the industry. In order to discourage the concentration of
investment in areas already industrialized, the government planners pro-
posed that Santo Domingo- and Santiago-based firms be allowed an 8- and
12-year exemption, respectively, while elsewhere exonerations were
extended to 15 to 20 years. Although the plan was to encourage indus-
trial dispersal, create new jobs in smaller cities, and, thus, slow
urbanization in the metropolitan areas, nevertheless, many of the new
industries established under the law were capital intensive. Only 9,400
new jobs were created in a decade when population increased by more than
one million (Bell 1981, 349-351).
There are 10-20 rural laborers underemployed or out of work for
each small farm. The goal of the agrarian reform program begun in 1962
was to improve rural living conditions sufficiently to stem the flow of
farmers whose numbers threatened to inundate the provincial and regional
capitals. From 1960 to 1970, the national population increased from 30
to 40 percent, and Santo Domingo almost doubled in size (RepUblica
Dominicana 1971b, 26). An annual urban growth rate of 5.9 in the capi-
tal was well above the annual national rate of 3.6 (Davis 1972), an
indication of the magnitude of rural-to-urban migration.
By 1975, another 200,000 migrants are believed to have moved into
Santo Domingo. Most are believed to have been without jobs and poor.
They probably became new residents of such marginal settlements as
those that have clung to the steep banks of the Ozama River where at
least 200,000 may have sought shelter (Fanger 1978, 26).
The Housing Problem
Residential land use is a reflection of demographic conditions
and, although not directly tied to economic conditions, is nonetheless
often the largest portion of urban investment (World Bank 1978, 285).
The traditional values manifested in urban institutions as well as the
particular social and economic conditions of city life have caused
rapid in-migration to cities. Where urbanization has outpaced the
expansion of the housing sector, severe housing shortages have occurred.
In the Caribbean, the rate of absorption of land into urban use
has increased less rapidly than the rate of population growth. The
requirement for space is a function of the total urban population and
the density or intensity of use for diverse urban activities. Land
development often includes the loss of open space, some of which is
vital for groundwater recharge, recreation, future urban growth needs,
the control of pollution, etc. The horizontal sprawl of cities in-
creases transport costs, the need for streets, water, sewer, electric-
ity, telephone and other utility extensions, provision of more clinics
and hospitals, more schools, more fire stations and police barracks,
more branch stores, supermarkets, etc. This expansion requires both
land and capital whichmay be severely limited. Improving municipal ser-
vices often can be accomplished more cheaply and consume less land by
intensification than by extension (Lamm 1973). By connecting addi-
tional utility customers on existing systems, adding more floors to
hospitals, schools, and police stations, it is possible to conserve
land, while savings in costs can be used to improve housing for the
Since the growth of population and structures will lead to changes
in a city's structure, residential land use has been of principal con-
cern to those investigating or seeking control of urban land use
(Bourne 1981, 19). There is the advantage to property owners, mortgage
investors, realtors, and others of knowing the probable or alternative
patterns of city growth.
Unlike the Anglo-American experience where climate and absence of
adequate housing have acted as a constraint on urbanization (Forrester
and Mass 1975, 25-26), conditions in Dominican cities have not impeded
in-migration (Makowski 1975, 55-56; Aversch and Levine 1971, 157).
Widespread, endemic poverty coupled with a moderate, subtropical cli-
ate allowsyear-round occupancy of rudimentary shelter, fostering exten-
sive marginal housing.1
Forrester (1974, 22-24) suggests that housing supply may be re-
lated to stages of urban growth, exerting an independent effect on inter-
urban migration as the city progresses through the industrialization
phases of modernization. If this is the case in Santo Domingo, then
Dominican urban problems may be similar to those experienced in Anglo-
American cities at the turn of this century (Herbert 1973, 36-45). But
unlike the latter places, the island capital has far less capital and
access to resources to engage in the similar solutions to housing de-
There is an important difference between the U.S. urban situation
in housing and that found in Santo Domingo. In the former cities, there
is an excess of deteriorated, even abandoned buildings, while in Santo
Alonso (1971, 4) prefers the term marginal. See John Collins
(1973, 118) for a discussion of other terms: squatter emphasizes
legalities in obtaining shelter; shantytown implies certain physical
conditions; uncontrolled urban growth is preferred by Collins because it
implies the interdependence of physical, social, and economic factors.
The latter choice also implies planning which is generally lacking in
Domingo, there is simply no housing available for the majority of those
requiring it, at any price, and certainly not within the means of most
urban poor. The spread of cardboard and palm-thatched huts is the mar-
ginal dweller's response to unsuccessful housing searches. As long as
vacant urban land exists to accommodate these poor people, it is likely
that the inflow of more people can be expected to continue. Assuming
that the Dominican population was over five million and that the average
family size was five persons in 1974, the Secretary of State for Health
and Public Welfare estimated the national shortage as nearly 400,000
units, of which 30-50 percent was located in Santo Domingo (RepOblica
Dominicana 1974; Fanger 1978, 26; Sanchez Cdrdova 1975, 42).
Five agencies participate in the Dominican housing program: the
National Housing Bank, the Technical Office of the President, the
National Institute of Housing, the Institute of Public Housing, and the
Savings and Loan Bank. Combined annual production of housing has
averaged 3,000 units, 1,000 of which were built in the capital. There
is a yearly increment in the demand for housing of about 10,000 units.
In the 1975-1985 decade, it has been projected that 115,000 more hous-
ing units will be required to prevent a further increase in the present
shortage. At a conservatively estimated cost of RD$ 4,000 per unit,
the annual cost would amount to RD$ 45 million, well above the expendi-
ture now being made for housing (Table 2-1).
There are approximately 200,000 households in Santo Domingo, and
only about 42 percent of them are able to obtain housing within the
commercial market. Less than half of all families needing housing were
able to quality for the minimum standard provided by those agencies
actively participating in the housing construction industry (Fanger
1978; Alonso 1971, 7; Sanchez C6rdova 1975, 42). The rest, numbering
over 100,000 families, have had to house themselves, often in marginal
settlements comprised of structures costing one-third of what is con-
sidered the minimum standard home. It is reasonable to assume that 70
percent of all housing each year has been improvised from discarded or
nearly worthless materials; only about 10 percent of these ranchos are
of the permanent type incorporating some concrete or other substantial
building material (Sanchez C6rdova 1973; Sadove 1973, 30; Turner 1967,
168; Vernez 1973, 23, 61).
In 1969, almost half of all public investment in new construc-
tion was made in loans to state-owned but decentralized (so-called au-
tonomous) financial institutions which spent about RD$ 2 million out
of RD$ 80 million on housing. These loans had to be secured, and they
were issued to recipients who had dependable, stable incomes, usually
the middle- and high-income residents, not the unemployed or under-
employed poor (Academia de Ciencias de la Rep6blica Dominicana 1977).
Government efforts to expand low-cost housing construction, ini-
tiated in the late 1950s, faltered during the mid-1960s and have since
tended to favor the small portion of the urban low-income population
that has secured reliable employment and is able to afford public hous-
ing remote from the commercial and industrial areas of Santo Domingo
(Vernez 1973, 95-100; Fanger 1978, 26-27; Crassweller 1966, 373-374).
Aspiring middle-class residents are following the same pattern as
extension of urban infrastructure underwrites more distant development
(Vernez 1973, 28; Kaiser and Weiss 1968, 57-58). As the population of
bureaucrats, business people, and technicians, who comprise the middle
class, expands, suburban development is expected to occur, but presently
they are often the occupants of public housing (Sadove 1973, 29;
Turner 1967, 167-168, 179; World Bank 1972, 30). The use of interior
space, the choice of location, the cost and the financing arrangements
for mortgages, have contributed to making public housing unacceptable
to or unobtainable by low-income families.
In 1970, RD$ 89 million in public funds were spent on construc-
tion, but only 3.5 percent was for new housing, much of it in the capi-
tal. By 1975, public expenditures for all new construction was
RD$ 251 million, 68 percent for housing (a cost-of-living index at 100
in 1969 rose to 188 at the end of 1975). In addition to losses due to
inflation, land speculation and widespread corruption within the con-
struction industry absorbed substantial proportions of the RD$ 31.6
million committed to the capital's share of new housing (Academia de
Ciencias de la Repdblica Dominicana 1977; Bell 1981, 187-189). Since
that peak housing construction year, rising fuel prices and high infla-
tion have curtailed public investment in housing.
Denied access to either the government or commercial housing mar-
kets, the poor people in most Caribbean cities have shared cramped
quarters with kinspeople and erected shacks throughout the city. Often
such spontaneous or self-help housing is built on land owned by the
government or in squatments where ownership rights are blurred. Such
settlements may have few if any municipal services (Turner 1967, 168;
Alonso 1964a; Havens and Flinn 1970; Vernez 1973, 12).
It is true that marginal housing is being replaced by other kinds
of housing. Since public funds loaned by autonomous financial agencies
tend to go to the construction of high- and middle-income housing, urban
renewal in Santo Domingo resembles renewal in U.S. cities during the
1960s and 1970s. The deteriorated areas were demolished, some to be
rebuilt in high-rise and expensive apartments, others to remain as open
spaces. In either instance, poor residents were displaced, forced to
move into other neighborhoods. The new residents increased demands on
already inadequate services and facilities, and higher densities led to
more congestion. Further deterioration often resulted in these communi-
ties (Bourne 1981).
Because urban land is limited, there is a tendency toward higher
density settlement in rapidly urbanizing cities. Much of the growth of
Kingston's population lives in densely settled, substandard housing
either in the center city slums or in peripheral marginal housing areas
(Clarke 1975, 96-97). It is believed that one-quarter to one-half of
Santo Domingo's population lives in downtown tenements and dense neigh-
borhoods at the city fringe (SAnchez C6rdova 1975; Fanger 1978). Follow-
ing the 1975 hurricane that flooded and devastated a large expanse of
marginal housing on the Ozama River floodplain, a plan was proposed to
resettle about 100,000 people living in a community illegally sited on
the bank of the river.
There is the belief in Caribbean capitals that squalor constitutes
the prevalent condition in marginal housing areas although there is
clearly difficulty in determining what standards ought to be applied to
defining substandard housing. Often the official position reflects
values that are unrealitic and hardly shared by the bulk of inhabitants
of these cities. Recent Dominican governments have been concerned about
the increase in people who are unemployed or underemployed and living
in the marginal settlements. Especially during elections, attention
has focused on these inhabitants who participate in the political pro-
cess (Bell 1981, 92, 124). But Latin American ecological research pro-
poses that the urban poor are not a homogeneous group and have varying
socioeconomic status and life-cycle stages which can be identified in
particular urban patterns (Gans 1968, 210; Alonso 1971, 4; Gilbert and
Ward 1978, 302-303; Turner 1968, 369; Mangin 1967, 68; Corten 1965, 5;
Souza and Porter 1974; Herbert 1973; Saf6 1974).
Turner (1968) considered the housing needs of low-income, low-
status inhabitants of several Latin American cities. Two patterns were
consistent. The poorest, usually the more recently arrived in-migrants,
were usually young, single, and with few marketable skills. They were
dependent upon accessibility to the employment opportunities in the
central business district and in the homes of middle- and upper-income
families. Given time, many of the inner-city poor acquired sufficient
experience to be employable in skilled, even permanent work. The re-
sulting improved economic condition permitted marriage and a family; the
new life-cycle stage required more living space. In the poor family,
however, housing is the largest proportion of the urban family's bud-
get expenditure (Sadove 1973, 29-30), and the minimum "low-cost" home
is beyond reach, so there is little opportunity in the commercial mar-
ket to acquire the needed space. Unlike the low-cost public housing in
Anglo-American cities which offers an alternative to the poor urbanite,
middle-income Caribbean families, caught in an extremely tight housing
market, have monopolized such housing. The result is that the poor
family must house itself by building marginally adequate homes on land
that is owned by others. In Santo Domingo, perhaps one-half of the
poor have moved into self-built homes (Sadove 1973, 29; World Bank
1972, 41; Bell 1981, 188).
There are at least three types of illegal housing settlements:
(1) those built on private or public land invaded by people who have
made no payment for its use; (2) the "pirate" housing areas constructed
on land sold in lots, legally, by entrepreneurs who have disregarded
municipal development codes that specify that basic infrastructural
services must be installed first; (3) the rentals erected by specula-
tors concerned for their otherwise vacant city land that is exposed to
possible squatter invasion (Turner 1967, 1968; Mangin and Turner 1968;
Mangin 1967). Whereas the third type is often a single house, the first
two types tend to occur at the city's edge in massive communities that
are often adjacent to middle- and upper-income developments.
Marginal housing at the city's edge tends to be occupied by the
more economically stable of the urban poor. These urbanites may have
moved several times in the process of making a long-term commitment to
purchasing a lot and building a modest home. It is a "step up" for them
and represents a substantial investment in a more secure future (see
Usandizaga and Havens 1966; Flinn 1966; 12-20; Vernez 1973, 16-20;
Turner 1968, 359). These marginal settlements are, thus, agents for the
social advancement of the poor just as home purchase in the commercial
market is a status decision for the other classes. Such settlements
house a substantial portion of the urban population in societies which
are slow to change and have failed to pace urbanization (Eyre 1972, 395;
Herbert 1973, 48; Turner 1966, 508-509; World Bank 1972, 41).
In the central business districts of these cities, the increased
competition for limited space is gradually transforming the traditional
plaza. The old homes of the urban well-to-do are being converted into
commercial and professional offices; the demand for rentals is resulting
in their conversion into apartments and rooming houses. The upper-
income residents who once preferred the convenience and excitement of
center-city living,with its old churches, parks, and proximity to work,
are opting for luxurious and fashionable new homes being built in pri-
vate residential neighborhoods at the city's edge (Grubb and Phares
1972, 14; Johnston 1971, 311-312; Eyre 1972, 397-398; Schwirian and
Smith 1974, 327; Quijano 1967, 11). This suburbanization, however, still
remains a minor phenomenon in some Caribbean cities.
Brown (1970) and Uzzell (1975) have found that where services are
available in the inner city, low-income residents exhibit much more
stability. They have resisted the efforts of landlords to evict them
in order to renovate or remodel buildings to house even larger numbers
of people. Consequently, the more recently arrived poor may have to
look for inexpensive housing further from the city center. This has
been substantiated by Ward (1976) who found that newly arrived migrants
tended to settle in the older, established neighborhoods rather than the
inner-city tenements. Similarly, Vernez (1973) discovered that in-
migrants moved into rented rooms in poor neighborhoods scattered about
the edge of the city.
Thus, at the city's edge, there are usually three types of hous-
ing. They are publicly financed housing, the high-income housing, and
the illegal settlements. The first two types are more orderly uses of
the land and result in regular patterns that accommodate the local
topography and the use of the automobile for transportation. Their neigh-
borhoods have curving streets which contrast with the rectangular grid
of the old neighborhoods of the colonial city. The illegal settlements
often leap-frog vacant land adjacent to the central business district and
spread out haphazardly across large areas at the city's edge (Turner
1968; Amato 1970; Vernez 1973, 25).
Social planners of the mid-1960s reacted negatively to these mar-
ginal communities, thinking them undesirable, the results of pathologies
of lower-income people, and debilitating to the health of the moderniz-
ing city (see, for example, Bonilla 1964; Shulman 1968; Berckholz 1963).
The prevailing belief persisted that home ownership is the major mechan-
ism for maintaining family ties and controlling social disorganization.
Furthermore, the prospective buyers of a home obligated themselves to
fixed monthly installments; occupants of marginal houses remain outside
the conventional world of planners and bureaucrats who wish to restrict
such residential land use. But public policies seeking to control mar-
ginal settlements have encouraged squatting. Slowly, officials have be-
gun to permit, even encourage, self-help housing constructed in areas
designated for planned "slums," in the hope that by doing so this can
preserve other open space for future development (Corrada 1969, 246).
There seems to be little doubt that marginal settlements at the
urban fringe have offered inner-city poor a way of improving themselves.
Given stable employment, the poor are willing to convert their wood and
cane shacks into concrete-block dwellings roofed with corrugated steel
sheeting and floor them in concrete. Continuing modernization is bring-
ing official acquiescence, especially legalization of claims to their
lands, and the introduction of municipal services-electricity, water,
sewers, street paving, garbage collection, police protection, schools,
medical clinics, etc.-over the years establishes and encourages these
communities (Turner 1968, 1976; Roberts 1973). There is much evidence
that land and home ownership are important values to the urban poor as
well as other, more fortunate city dwellers (Cornelius 1975; Lomnitz
1975; Stepnick 1979; Turner 1972, 1977; Mangin 1970).
URBAN SOCIAL DIFFERENTIATION
People residing in the city pass through several stages during
their lives that involve changes in their living habits. These changes
are manifested in land use patterns. For example, the selection of
housing is associated with changes in life stages. People are likely
to leave behind the neighborhood in which they were brought up and even-
tually move to another residential area in the city which facilitates
their changing roles as spouse, parent, career person, retiree, and
Because of the intricate nature of the city, the evolutionary se-
quences of city forms have been premised upon key, large-scale variables
that include population, institutions, environment, and technology
(Berry and Kasarda 1977, 14). The geographic assessment of urban change
involves formal and functional relationships which vary importantly with
differences in scale. The formal city incorporates such diverse phe-
nomena as land use, settlement patterns, and population dimensions.
Urban morphology is assumed to be evidence of functional relationships.
Urban form is culturally associated, but it also contains patterns
similar to those in all cultural milieux. At some point in time, these
forms may tend to converge into a single, general pattern (see Hawley
1971, 290-315 for a discussion of the urbanization process in develop-
Social geography of cities can be traced to early work in areal
differentiation and man-land geography, both of which often viewed the
urban environment as one of economic specialization (see Whittlesey
and Wellington 1925; Hartshorne 1959; Sauer 1941). The little atten-
tion given to the characteristics of residential change was due in part
to the emphasis on the features of places rather than population charac-
teristics. But the improvements in national censuses and availability
of such data encouraged social scientists interested in a wide range of
noneconomic processes to explain urban morphological change. By 1930,
more Americans lived in U.S. cities than in the countryside. Cities
had become the centers of change, and it increasingly became popular to
search for ways to innovate in shaping this growth.
The social differentiation of the city into patterns of concen-
tric zones that have spatial identity was founded on the work of early
sociologists Robert Park, Louis Wirth, and Ernest Burgess. Homer Hoyt
proposed a second, sector model; both the sector model and Park and
Burgess' concentric zone model were modified by others including
Chauncey Harris, Edward Ullman, and Amos Hawley, but these first two
models remain the "classical" explanations of urban morphology and
ecological differentiation. It is likely that they are not contradic-
tory but rather represent stages in city growth. Thus the concentric
zone model emphasizes change during a period when the city contains
many population groups at various points of assimilation. The sector
model describes residential patterns of cities that have progressed
further along a continuum of ethnic assimilation when prestige or
status become a significant determinant (Herbert 1973, 74). With
continued city growth, Harris and Ullman proposed that the relocation
of economic activities and population movement was fundamental to the
formation of multiple urban nuclei within the context of metropolitani-
Concentric Zone Model
The Park-Burgess concentric zone model, resembling a nineteenth-
century model of an agricultural market town devised by von ThUnen, was
influenced by the work of Hurd (1903) on central and axial urban growth.
Park and Burgess used the nonhuman ecological concepts of invasion and
succession through competition and dominance to explain human community
use of space (Burgess 1925). Thus the city was seen as a product of
environmental competition and interdependence characterized by the social
and geographic mobility of its heterogeneous population. Change in the
location of people and institutions and the subsequent social reorgani-
zation were explained as concentric circles delimiting zones of homo-
geneous socioeconomic level, density, and distance from the center of
an idealized city. The gradient, developed by Duncan and Duncan (1955,
396) became the model's index of centralization. A negative value indi-
cated a tendency for the group to be concentrated beyond the center of
the city; a positive value suggested a trend toward centralization.
The model is an application of the distance-decay principle of centri-
petal force inversely proportional to distance based upon inductive
generalizations about forces responsible for mobility in the city
(Burgess 1923; Park and Burgess 1921; Park 1925).
It has been shown that these zones are not as homogeneous as
Assuming equal accessibility in all directions, Park and Burgess
measured distances in units of time and cost (Quinn 1940, 212). Social
distance resulting in a circular ecological structure could thus be
consistent with a rectangular spatial configuration in which accessi-
bility would be determined by a network of intersecting streets at
Urban land, aggregated into four grades, was found to group into
concentric bands that were hypothesized to be internally homogeneous.
These were called zones, four of them encircling the commercial center.
In the central business district (CBD) is found the retailing establish-
ments including the main department stores and the chic specialty shops,
the central offices of major financial institutions, office buildings,
clubs, the headquarters of civic and political organizations, the
more expensive hotels, theaters, and museums. At the outer edge are
wholesale businesses including markets, light industry, and warehousing.
As the most accessible area, and with the largest daily number of trips
into and out of it, this zone contains the main transportation terminals.
Although when the city was youthful and growing this area was the site
of many fine residences, growth with increasing functions and result-
ing competition for limited space has left only a few pockets of hous-
ing which are much deteriorated and occupied by transients.
The second zone is adjacent to the wholesale district. Originally
the main suburban residential area for the city before the advent of
rapid transit and the automobile, it has been experiencing changes in
functions characterized by encroaching business and industry from the
CBD replacing the deteriorated housing. Landlords are either unwilling
or unable to maintain the tenements and remodeled houses. Neighborhoods
have changed and the few homes are badly outmoded. The rentals, in
tenements and rooming houses, are densely occupied by the newly arrived
migrants who are often unskilled, the very young and old, and survivors
of broken homes.
The independent working people occupy modest homes in the third
zone. These people desire proximity to employment in enterprises close
to the CBD, and they have had to trade off the amenities of living
further from the congestion of the city center for this accessibility.
However, the continued expansion of the CBD and the influx of new workers
tend to intensify land use in this zone, with the result that some of
the more fortunate in this area will invade the less dense, more de-
sirable residential areas farther from their present homes.
In the fourth zone are the homes of the middle class, people who
own and operate the smaller businesses of the city, the clerks and sales-
persons, the professionals who comprise the middle class in U.S. society.
There is no distinct boundary separating this from the next, outer zone,
unlike its other border contiguous with the working peoples' zone. For,
beyond this residential area can be found the small towns and hamlets
that are the dormitory suburbs of the city and in which reside high-
income commuters and their families. These commuters have chosen to
live here on the weekends, in segregated neighborhoods, and commute to
city-center jobs in long, daily trips or live in city-center apartments
during the work week.
Burgess identified two zones beyond the built-up area of the city.
The far-reaching agricultural district is within commuting range of
the city, while the hinterland extending beyond it still is linked to
the metropolitan area even though too far away for daily commutation
(Burgess 1930, 181-182).
The model assumes that urban population growth is due primarily
to in-migration, especially of low-income people seeking economic and
social improvement. This urbanization results in segregated housing as
the residential land use expands and new housing development occurs.
Newly arrived migrants tend to settle in the transition zone tenements
and rooming houses where rents are cheap, but densities are high and
conditions are often squalid. As in-migration continues, the housing
opportunities become scarce, both because of increased population and
the loss of structures to other land uses. Gradually these people are
forced to invade nearby low-income housing that has been vacated by
families seeking better homes farther out from the city congestion.
Thus, the process of change occurs on a gradient, the oldest urban
development closest to the CBD. The oldest neighborhoods are gradually
changed by this process of intermixing and sorting out that once again
establishes neighborhood stability with a different character.
Unfortunately, the condition of neighborhood homogeneity is con-
tradictory to the notion of a gradient in the value of social attri-
butes. Discrete, homogeneous concentric zones conflict with gradations
in income level, population density, etc., and human ecologists have
demonstrated that socioeconomic status increases with distance from the
center of the city. The model assumes that population density de-
creases from the inner to the outer zones. Dwelling unit density and
the percentage of home ownership have been found to increase with
distance from the CBD to the zone of most recent growth (and in the
1930s, this was 11 to 13 kilometers); beyond, both housing value and
ownership were found to decrease (Blumenfeld 1954). As the growth edge
moves outward, it carries the greatest concentration of activity and
experiences the most rapid rise in population density.
As long as the pressure for expansion and the resistance to inva-
sion are uniformly dispersed across the urban landscape, isochronal
lines of zonal growth move out from the city center in a circular pat-
tern. The pressure for housing in one zone leads to pressure on the
adjacent, outer zone, and each is transformed as people invade from one
zone to another.
The concentric zone model is a special case of a city with a cen-
tral business district, with sufficiently large population to permit
functional heterogeneity distributed in relation to work opportunities.
In that major employment center, city functions operate in a market
economy at the industrial/developed stage including the segregation of
activities based on minimum levels of accessibility. The older and
larger the city and the less active the growth, including the annexation
of new territory, then the more likely the "expected" pattern of the
concentric zones will occur (Schnore 1967).
Modernization has modified the conditions upon which Park and
Burgess formulated their model. The massive impact of automobile use
since World War II has greatly increased the extension of urbanized land,
has been directly responsible for strip development, and has made mul-
tiple centers of commercial activity necessary (Angel and Hyman 1972;
Richardson 1976). In some European cities, for example, the relocation
of industry near a source of cheap labor left the center of London,
Paris, and Moscow to the elite, while the poor were relegated to periph-
eral land on the outskirts of the cities. These patterns persist even
today in spite of post-war modernization (Hauser 1968).
There are topographical impediments to development in most urban
sites. But there are also such obstacles as historical inertia and
policies that tend to distort the ideal pattern that the concentric zone
subsumes. Thus, the functions which in a previous time were useful for
controlling change may persist even though they have ceased to be so.
Municipal ordinances may curtail certain kinds of growth. Vertical
space can become more important than horizontal space in the city that
has spread out so much that accessibility is at a premium and must be
stringently regulated. However, land use controls may not include air
rights protection nor encourage rational vertical development.
The Applicability of the
Concentric Zone Model to the Caribbean
In spite of criticism of the model, the concentric zone model re-
mains the principal paradigm explaining urban growth. Enough evidence
has yet to be collected, however, to assume the Caribbean capitals,
with continued growth and development, are evolving as suggested by the
idealized model. There have been some cross-cultural comparisons made
with Anglo-American and Asian, African, and Latin American cities (see
Hansen 1934; Hayner 1946; Caplow 1949; Dotson and Dotson 1954; Hauser
and Schnore 1965; Schwirian and Smith 1974; Clarke 1974; Schwirian and
Rico-Velasco 1971; Turner 1968, Mangin 1967; and Alonso 1964b for Latin
From a study of the literature about ecological patterns in Latin
American cities, Schnore (1965) concluded that there is an evolutionary
process of urbanization including residential patterns indicative of
social differentiation. The socioeconomic status of neighborhoods
gradually changed with development to assume the concentric zone con-
figuration. In the more traditional cities, the higher-status group
preferred city-center residences; however, with modernization (and all
of the cities displayed change in this direction), the upper class
vacated their older city residences for new homes built on larger land
parcels at the city edge. Schwirian and Smith (1974) found that in the
smaller Puerto Rican cities, social status was negatively associated
with distance from the CBD, while in San Juan, there was a reversal of
this pattern as well as decreased density of residential neighborhoods
with increasing distance from the city center. Clarke (1974) found some
evidence for the same patterns in Kingston; however, there did not
appear to be a commuter zone, and the transition zone was difficult to
demonstrate. The social status gradient held true generally except for
the peripheral "shantytowns" and public housing developments (Clarke
Turner (1968, 359-360) considered the applicability of the Park-
Burgess model to low-income, low-status housing in Latin American cities.
Two patterns were consistent: The inner area in the zone of transition
which houses the poorest and the newly arrived followed the model; an
outer, peripheral area of poor inhabitants exists, however, which is
inconsistent with the concentric zone hypothesis that proposes a com-
muter zone of well-to-do residents. Turner (1968, 360) labeled the
inner-city poor as bridgeheaders, and described them as barely skilled,
largely unemployed upon arrival,and dependent upon the few jobs to be
found in the central city businesses and in the homes of middle- and
upper-income residents. Turner identified another group at the perimeter
of the city as consolidators, poor people who had apparently secured
more permanent employment and were able to forego city-center proximity
to improve their housing situation.
Such research, which seems to conflict with the concentric zone
model, in fact, may not indicate that the model does not apply to Latin
American or Caribbean cities. Evidence exists for an evolutionary se-
quence in the development of urban residential structure. Schnore (1963)
computed the age of Latin American cities from the decade in which they
achieved 50,000 in population, concluding that it appeared the best pre-
dictor of urban spatial structure. The smaller, and thus younger, city
was likely to have high socioeconomic-status people living in the city
center. With time and increased population, decentralization becomes
pronounced: the middle class often establishes residence at the urban
periphery first, but, once its numbers become sufficiently large, is
soon followed by the upper class. Schnore attributed the differences
between young and old cities to the nature of the housing market. In
central cities' older areas, there are many obsolete buildings, whereas
in young cities without such older, inner neighborhoods, there are many
high-status buildings because decentralization has not been present
long enough to encourage extensive growth of a transition zone. With
such growth and expansion of the urban core accompanied by improved
accessibility, the upper class will vacate the center city, leaving
behind their homes which are modified to accommodate low-class residents.
Schnore (1964) pointed out that larger, older cities which used
annexation less often to accommodate growth were more likely still to
exhibit the expected concentric zonation. Thus, the more rapidly grow-
ing the urban center, the less likely that concentric zones will per-
sist; the older, larger cities display the most apparent Park-Burgess
concentric zone pattern.
Although Davis (1969) disagreed with Schnore on the sequence of
out-migration from the city center pressured by urbanization, both
researchers concur in an evolutionary model of residential change that
consists of four stages. There is a preindustrial stage when the city
is small and growing slowly. The elite resides adjacent to the central
business district. In the industrial take-off stage, urbanization is
accompanied by transportation innovation promoting improved accessi-
bility. The upper class is able to move to the edge of the built-up
zone. The lower class dominates the inner zone, and the middle class
is left intermediate to these two. In the third stage,which is a
continuation of industrialization, increased pressure for change in
residential areas is prominent. A new elite, emerged from prosperity
based on industrial expansion, can afford and demands new, luxurious
housing. Innovations in housing technology result in obsolescence.
As the process of occupancy change called filtering permits other,
less affluent people to occupy once high-income homes, a pattern of
decreasing status toward the CBD results. The general prosperity
encourages expansion of the middle-income group and leads to more clearly
defined zones of socioeconomic level. The fourth stage is postindustrial,
characterized by stable residential patterns. Growth is most conspicu-
ous in middle-income suburbia which encircles the older, high-income
area at the fringe of the city's built-up land.
In studying Latin American cities, Amato (1974) failed to identify
a middle-income group intermediate to an inner-city, low-income zone
and a suburban high-income zone. Rather, the elite lived in low-
density, dispersed neighborhoods, all of which were approximately equally
distant from the center city. The middle-income group lived in closest
proximity to the CBD at relative high density, suggesting their willing-
ness to exchange space for accessibility. The low-income neighborhoods,
also relatively dense, were more dispersed and at locations farther out
than the middle-income neighborhoods.
Individual urban communities, i.e., inner suburbs and outer sub-
urbs in a metropolitan area, may also differ in development stages at
any particular point in time. Wils (1974) suggested that it is possible
that urban conditions measured during recent censuses, for example, may
reflect a single stage of development. Thus, studies of Latin American
cities restricted to very recent data collections may fail to support
an evolutionary model of urban spatial structure only because the
period of information gathering is short by comparison with the Anglo-
American research base of census data extending well into the nineteenth
century for many coastal cities. If a general theory of urban spatial
structure is to exist, then researchers must consider the possibility
that cities may be at various development stages and moving toward
experiences similar to those of Anglo-American and Western European
cities. Preindustrial cities do not display as clear a differentiation
of residential neighborhoods according to socioeconomic and life-cycle
status as do postindustrial cities. Comparative studies of spatial
structure in other cultural milieux are needed to substantiate present
theory (Herbert 1973, 178-179; Abu-Lughod 1969, 209-211). As
Johnston (1971) stated in his review of the literature of urban spatial
patterning, the concentric zone model is incomplete and contradictory.
The effect of population growth and modernization on the urban fringe
remains unclear to him as well as to students of Caribbean urbanization.
Hurd (1903, 59) noted that city growth was evident in two patterns,
central and axial, which ranged outward in all directions from the city
center provided there were no impediments to development. Such growth
tends to parallel transport lines, making adjacent land more valuable
because of improved accessibility. The evolutionary character of growth
results in the obliteration of the physical evidence of unequal growth
in the immediate advance of central growth, but a star-shaped configu-
ration persists in the wake of axial expansion ahead of the main city
In the 142 U.S. cities which Homer Hoyt (1939) examined, railroad
and water transportation routes attracted industry, and local residen-
tial growth accompanying industrial expansion tended to extend out from
the center of the city in a wedge-shaped pattern. The prevalent wind
direction carrying industrial airborne pollutants reduced the desira-
bility of land in its path for residential use. Land that escaped this
pollution was sought after, often by the well-to-do; once established,
the high-income neighborhoods tended to remain homogeneous as they
expanded outward within a sector bounded by transportation corridors
(Hoyt 1939, 53-58). A slowly urbanizing city was expected to have much
central expansion and less active axial growth and fewer outer settle-
ment nuclei along transport lines. A rapidly growing city, by con-
trast, would expand overall, intensifying land use in both axial and
central development including filling in during this growth process.
Residential land use intensification included vertical growth and
the change from single- to multiple-family, higher-density structures,
the development of what had been vacant land, and the outward exten-
tion of the city perimeter. Hoyt (1939, 69) identified the high-rent
residential area as the initiator of expansion and the force attract-
ing all other housing on a gradient of rental based on land value; the
gradient sloped downward in all directions from it. Originally sited
near the retail and office center which was close to employment and
usually far from industry, the high-income residential sector encom-
passed a relatively large area for the number of people housed within
it. But the desire for upgraded neighborhoods, modern living condi-
tions, little or no congestion, and other beneficial attributes induced
people with means to relocate farther out along nearby transportation
corridors which provided accessibility and rapid journey-to-work routes.
Often these routes extended to more distant commercial centers.
Usually the best land was selected for the high-income housing.
It was best when sited at a high elevation, commanding a fine view,
safe from flooding, and accessible to cooling breezes. The best land
could be found along unspoiled waterfronts, and wherever there were few
natural barriers to transportation. Such land, once established as the
upper-class residential area, with continued urbanization would even-
tually extend outward in a wedge from the CBD. The direction of this
expansion resisted change although real-estate promoters were known to
modify the trend by convincing city leaders to relocate elsewhere out-
side the sector (Hoyt 1939, 69-71).
In the portion of the sector closest to the CBD and which was
being filled in change persisted. Luxury apartments were built on
cleared residential land. Immediately adjacent land on either side of
the sector tended to accompany outward extension of the wedge. At any
distance from the city center, mutually exclusive activities competed
for space, i.e., manufacturing concerns and multiple-dwelling struc-
tures, but inertia helped to preserve the integrity of the sector's
homogeneity in both social class and land use. In the ideal form of
the model, Hoyt proposed that the sector was actually heterogeneous due
to invasion and succession which modified the land use intensity. Thus,
for example, the upper-income sector would include specialty shops
catering to its well-to-do customers, expensive high-rise apartments,
older luxury apartments, elaborately constructed homes,and those indus-
tries such as hospitals and laboratories which employed professionals
who could afford to live in these communities.
The Applicability of the Sector Model
to the Caribbean
In a later assessment of the sector model's applicability to
Latin American cities, Hoyt (1963) found that single-family homes of
the elite and their luxury apartments tended to concentrate in one side
of a city. The sector model incorporates a growth process for expan-
sion of the sectors. Increased demand leads to development that is
simply added to the outermost portion of the wedge. Thus, as Latin
American cities became crowded, urbanites migrated outward from the
center city to new housing constructed at the urban edge but within a
sector already established as predominantly homogeneous in socio-
economic status. Amato (1974) demonstrated that Bogota was continu-
ing to develop along the same sector pattern identified by Hoyt. The
elite remained on the east side of the city opposite the industrial
development. Vernez (1973) found, however, that marginal housing
settlements competed for land at the periphery of Bogata,and assumed
that over time there would be further evidence of the trend toward
heterogeneous residential growth. Nevertheless, he concluded that
Bogata was growing "somewhat along the lines of Hoyt's theory of urban
development" (Vernez 1973, 22).
The sector model suggests that high-income residents are the
trend setters and the most important participants in residential land
expansion, establishing both the timing and direction of growth. In
both Latin American and Caribbean cities, new residential areas often
exhibit California-style ranch homes built in closed developments that
include shopping centers, churches, private schools, and extensive
street networks. The occupants were once inner-city residents who lived
in colonial mansions since remodeled as multifamily units and occupied
by middle-income renters.
The expansion of elite residential areas often occurs along higher
elevations where climate and view are best and where the homes are most
distant from the noxious industrial and commercial activities. Portes
(1977, 68-69) concluded that isolation and space are as important to
the Latin American elite as they have been to the well-to-do in Anglo-
American cities. Once ensconced in their exclusive communities, they
are served by fine highways and paved streets, municipal services, and
private commercial and professional services. Increasingly, sharp
divisions along socioeconomic lines are segregating Latin American
cities (Portes 1977; Gilbert and Ward 1978).
Economic growth in Latin America since World War II has included
expansion of management opportunities and the professional services,
resulting in growth of a middle class (Gilbert and Ward 1976, 287-288).
These urbanites have access to most social services, consumer goods,
recreation, and good housing.
Aspiring, middle-income urbanites in Latin America have been
found to seek out housing close to the elite sector (Johnston 1971).
Besides the status which accompanies residence in such neighborhoods,
there are substantial advantages to middle-income communities which
are able to utilize the transportation system servicing the elite as
well as municipal services extended to the homes of the well-to-do at
the urban fringe. Since middle-class renters occupy the remodeled
center-city mansions left by migrating high-income residents, Gilbert
and Ward (1978, 295-298) have concluded that this socioeconomic group
is becoming a major influence in determining residential patterns in
Latin American cities.
Much criticism of the sector model has centered on its descrip-
tive nature (Firey 1947, 86). It is believed that cultural and social
explanations exist for human adaptation to physical space. Thus, loca-
tional behavior is directly determined by the values of the social
milieux with associated activities the result of rational assessment of
the environment. Alonso (1964b, 227-231), in a reinterpretation of the
concentric zone and sector models, dismisses them as historical explana-
tions. Rather than accepting the processes of invasion and succession
for the changing socioeconomic patterns, he offers a structural hy-
pothesis which assumes neighborhood choice is a result of one's prefer-
ences. Such a criticism appears to ignore Hoyt's emphasis on choices
made by social groups as determining residential site selection and
thus patterns of urban morphology.
Multiple Nuclei Model
The most desirable points in a city are often those most accessible
to other points. On the theoretical economic plane, that locus is the
central business district, ignoring the influences of speed and mode of
transport (Odland 1977, 3; Hamburg and Creighton 1959, 68). The CBD is
assumed to draw the labor force to the major employment opportunities.
These lines of communication include numerous points of unusual activity,
i.e., breaks on transit lines where there are connecting routes or
changes in the mode of transport. At these sites, establishments
serving the commuters will proliferate. Over time the agglomeration
attracts more activities until the emerging node may include industry,
businesses, schools, residences, recreation facilities, etc. At the
center of such diverse activities, a node becomes stable and begins to
generate its own traffic, thereby contributing to the growth of a city.
Such expansion in a series of many nuclei is the contribution that
Harris and Ullman made to understanding urban spatial structure (Harris
and Ullman 1945, 14-15; Mayer 1969, 33; Hamburg and Creighton 1959, 68).
The initial nucleus in a city will have been based on such func-
tions as defense, transportation, administration, education, religion,
mining, manufacturing, recreation, marketing, etc. But the appearance
of separate nuclei is due to one or more of four conditions. Certain
activities require specialization, others profit from cohesion, still
others experience exclusion because their activities are detrimental
to neighbors, and, finally, there are activities that cannot afford the
more desirable locations and must opt for remaining space (Harris and
Ullman 1945, 14-15).
Multiple nuclei, therefore, tend to be homogeneous in their func-
tions, at least during their initial formation. They are also primarily
phenomena of the metropolitan area rather than the central city
(Anderson and Egeland 1961, 394). Beyond the central business district
where accessibility is less and rents are lower, a wholesale and light-
manufacturing nucleus may develop along a transportation route at a
crossroad. A heavy-industry district may be sited at the edge of the
city. The cultural and entertainment centers and outlying business
districts may become other, minor nuclei. The residential district re-
quires some measure of accessibility, but is selective of topography and
nuisances (Harris and Ullman 1945, 15).
It is likely that Anglo-American cities and their metropolitan
areas have manifested aspects of all three models of urban spatial
structure. The zonal model has been confirmed as characteristic even
where sectoral change dominates (Johnston 1971). In most cities, how-
ever, there is a clear sector patterning of socioeconomic status of
the urban population. Berry (1965, 100) concluded that the three models
contribute independently to the understanding of the socioeconomic
structure of neighborhoods. Herbert (1973, 74) proposed that the hy-
potheses may represent stages of growth. The concentric zone model
represents the early stage when the city was more homogeneous in popu-
lation and activities. Development and the reduction of social dis-
tance caused the neighborhoods to expand sectorally. Eventually a
multiplicity of activities and the extension of transportation corri-
dors induced the competition of other centers.
The Applicability of the Multiple Nuclei Model
to the Caribbean
Since multiple nuclei are primarily associated with large cities,
it is apparent that in an evolutionary scheme explaining land use change,
the city will have had to experience extensive development for condi-
tions to have occurred that made multiple muclei possible. Thus, the
city that experienced both vertical and horizontal expansion would most
likely exhibit such a configuration.
When models fail to predict spatial structural change, reasons
include modifications of the present market system, the introduction of
some artificial constraint on free-market forces of supply and demand,
or the slowing down of urbanization. Increasing governmental interven-
tion including such regulatory policies as planning and zoning ordi-
nances can modify the expected zone or sector change. Even the spread
of prosperity to other urban groups can result in decreasing social
distance and cause residential neighborhoods to become heterogeneous
Johnston (1971, 195-196) noted that a major criticism of socio-
economic evolutionary urban models of residential land use is the
failure to account for cultural values that are important for indi-
vidual examples; however, on a broad scale, these three hypotheses of
urban spatial structure may serve as a baseline for generalizations
about urban change.
An essential research area that remains to be adequately explored
is the applicability of these theoretical constructs on a cross-
cultural sweep, for general theory building requires that behavior be
predictable under universally measurable conditions. In consideration
of the common Western heritage and interaction among peoples of North
American, it should be possible to expand our knowledge of urban experi-
ences that share interregional similarities. Identifying such common-
alities is a necessary step in isolating and identifying the general
causes of urban change. Planning for this change in the Third World is
becoming critical under the mounting pressures of urbanization in the
Caribbean and Latin American and the future likelihood that the phe-
nomenon will spread to Africa and the Far East. In the Caribbean as in
the rest of the developing world, limited space and scarce resources
will permit few mistakes in preparation for the societal changes that
will accompany urbanization.
IDENTIFYING LAND USES AND HOUSING CONDITIONS
Aerial Photography Data Base
In addition to being the largest city on the island of Hispanola,
Santo Domingo is the regional capital and administrative seat of the
National District which extends into a rural hinterland well beyond the
metropolitan area. Local conditions and associated problems of a
large city are of concern to officials of the municipality, but their
proposals have not often taken precedence over regional and national
considerations involving city resources. The need for boundaries which
help define responsibilities of city departments and limit urban in-
frastructure has been recognized by national leaders. In September
1975, President Balaguer submitted a national commission's proposal for
the city's future growth to the National Congress which included a
message in which he explained that such a plan was needed to stem the
horizontal spread of Santo Domingo.
The proposal included 16 articles, the first of which defined the
city borders which enclosed an area of approximately 80 square kilo-
meters. The third article called for the periodic revision of these
limits, while the fourth specified the need for an inventory of land
use. The most politically sensitive issue addressed in the proposal
was the suggestion that land developers would have to pay for the exten-
sion of municipal services beyond the city borders.
For purposes of this research, the study area was extended be-
yond the national commission's recommendation in order to include
developed land that appears on the aerial photographs as linked to the
urban communications network and is close to the contiguously built-up
city. The preliminary study area was 16 kilometers wide, stretching
from the residential community of San Francisco in the west to Reparto
Isabelita in the east, and 9 kilometers from the Caribbean coast to the
Isabela River at Puente de Pontones. The site is about 144 square
kilometers and is outlined in Figure 4-1.
Temporal and Spatial Framework
The aerial photographic coverage in 1948 and 1974 was selected
for interpretation. Prior to World War II, most of the urbanized area
was confined to the colonial center and contiguous land to the north
and west of the old city walls, and included the communities of La Fe,
Mejoramento Social, Naco, La Esperilla, and Villas Agrfcolas. There
was little development on to the east bank of the Ozama River, and the
large airport impeded extension at the western edge. The earliest
postwar photography, in 1948, was chosen as the base year for analyz-
ing land use change in order to demonstrate the city's spatial patterns
shortly before extensive areal growth occurred. The 1948 photography
reveals a city limited to an area contained between the Andrews Air
Force Base in the west and the Ozama River in the east, with a few,
scattered buildings along the eastern bank of the river. The popula-
tion of Santo Domingo is estimated to have been less than 250,000 in
that year. The colonial center and the area to the north, in what
was once a rural village called San Carlos, are the most clearly
4,s' g I
44 W .
.1 *, ~
__ _ __ _ __ _ __ _ U." I I i
defined developed areas. The transportation network does not extend
much beyond these except as unpaved streets with widely dispersed
houses. Undeveloped plots are scattered throughout the build-up city
lying outside the colonial walls.
In 1974, there were three times as many people living in Santo
Domingo which covered an area five times as great. The airport had been
removed, eliminating a major impediment to growth to the west. Paved
streets, two new bridges which replaced the single span over the Ozama
River, and portions of a circumferential highway were in evidence. Al-
though there appeared to be less open space interspered with developed
land, there was much undeveloped land at the edge of the built-up city.
Since land use information obtained by sampling the city was to
be correlated with that obtained from the analysis of the aerial photog-
raphy, it was necessary to devise a land use classification which would
permit interfacing the survey data with the type of development, and
indicators of socioeconomic level with the remote sensing information.
The aerial interpretation was structured so that the land use cate-
gories would coincide with the field survey land use designations.
There were three data bases: the 1948 and 1974 aerial photography and
the 1975 field sample of streets in the capital. All land use informa-
tion and a measure of distance from the site to a central point were
aggregated into one-hectare cells of a grid system centered at the
central business district. A 1973 city map of the transportation net-
work served as a base map. Figure 4-2 shows the steps taken to analyze
both the photography and field information. Interpretation of the
former data bases produced land use and land use change maps. The
Figure 4-2: Flow Diagram of Research Methodology
field survey included more than 140 streets and over 9,100 sites, all
of which were mapped. An overlay of hectare-sized cells was used to
sort the data which were merged with the aerial photographic data.
Factor analysis of residential land use produced three important fac-
tors defining socioeconomic levels of housing.
Five land use categories were selected: low-income residential,
medium-income residential, high-income residential, open space, and
other use, which was a combination of commercial, industrial, and pub-
lic uses. The aerial photography was interpreted before the field re-
sults were analyzed, and the field sample variables were taken into
consideration in establishing the residential land use groupings.
Residential land use was segregated into three socioeconomic
levels based on a variety of conditions which were included in the 1970
Population and Housing Census and which were believed to discriminate
among the broad income levels. Previous work by Thruston (1953),
Rapoport (1969), Cortdn (1965), Openshaw (1969), Amato (1969), Johnston
(1969), Eyre (1972), and Vernez (1976) suggests that there is a rela-
tionship between socioeconomic class and building materials used in the
homes constructed for the occupant families. For example, the
colonial-type house resembling the courtyard-centered structure familiar
throughout Spanish America can be found in Santo Domingo. A large,
several-storied, European-type house is found with a wide range of
exteriors dictated by style changes over the years. The American
ranch-style house is built by middle- and upper-income owners who
desire the modern conveniences which accompany these residences.
Popular, multiple-family housing for middle- and high-income
urbanites, often found in the center city in the form of high-rise
buildings, offers the advantages of convenience and excitement so im-
portant to those who relish city life. Another housing opportunity for
the middle-income families is public housing. Although ostensibly con-
structed for low-income families, nevertheless, public housing projects
often become middle-income neighborhoods whose relatively affluent
occupants, the bureaucrats, professionals, and technicians of a modern-
izing society,are much more desirable tenants than poor people with
Low-income housing varies considerably. Single-family, low-income
homes are often simple, one-room shelters at first, usually no larger
than 30 square meters and constructed of wood, recycled materials, and
palm thatch. Subsequently, as the family income stabilizes, the occu-
pants may improve their homes. Wooden and cardboard walls are replaced
with concrete blocks, and the roofs are weatherized with galvanized
steel sheeting. The dirt floors of the original homes are covered with
cement. Cement is the most popular, least expensive building material
for improvements which may include the addition of a kitchen and bed-
rooms, and even space for a small business. Eventually, the lot sur-
rounding the homesite will be fenced to protect a garden plot. Over
several decades, the home may increase in size three to four times.
Community densities of 200 to 500 persons per hectare are not uncommon
in low-income neighborhoods (Vernez 1976, 9-11).
Large poor populations often receive the attentions of municipal
officials who were once disinterested in the problems of only a few
needy families. The older, more permanent low-income communities have
paved streets, curbing, sidewalks, schools, parks, and even sewer and
water connections. In Santo Domingo, for example, electrical service
is available throughout the metropolitan area and is the result of an
ambitious national hydroelectric development program that is provid-
ing extensive if unreliable electrical service to the city. Although
the lines may be illegally tapped, nevertheless, most low-income neigh-
borhoods have power.
The residential land use categories were finalized after con-
firming that these features of housing were visible on the aerial photo-
graphs. Land use was determined for each cell of a grid overlay of
hectare-size units positioned over the aerial photographs to coincide
with a grid of units of equal area drawn on a 1973 city map prepared by
the Geographical Institute of the Autonomous University. The follow-
ing characteristics were used:
1. Low-income residential structures are small, usually less
than 100 square meters; they have no landscaping and no evi-
dence of automobile ownership; roofs are constructed of palm
thatch or steel sheeting; they have few building edges
(indicating a small number of rooms); they are closely sited
with little or no open space between; they are close to a
rectangular network of streets and connecting, serpentine
pathways; there are few paved streets; there is frequent
irregularity in building alignment. Where the majority of
structures in the hectare could be so grouped, the use was
deemed low-income residential.
2. Medium-income residential structures have concrete, tile, or
asbestos roofs, there is much open space between buildings
indicating moderate to low density per hectare; the struc-
tures may be landscaped; the lots are often fenced but do
not include garden plots; there are driveways and carports;
there are many edges to the structures; there is a regular-
ity in the alignment of buildings and streets which often
form a rectangular grid.
3. High-income residential housing is significantly different
from the other two groups. There are very low densities,
often one large building to a hectare; the structure has
many edges, extensive landscaping, driveways and fencing;
it is found in areas that have rectangular and curving
street patterns that suggest much use of the automobile.
Terrain that is sloping is desirable because of the privacy
and ambience it affords, and the land is often heavily
wooded. There is a general absence of commercial and indus-
trial activity which includes parking for numerous automo-
biles, large buildings with few edges, proximity to well-
traveled highways, pollution, and little landscaping.
Other use was the category with the greatest variety of activi-
ties, including government, commerce, manufacturing, and any other
urban, nonresidential purposes. Indicators include high density of
very large, many-storied structures with only a few edges, proximity
to similar structures, much automobile parking space, extensive
storage area, evidence of congestion and pollution, accessibility to
transportation, large machinery, and absence of landscaping.
Open space is indicated by the absence of development. When over
half of the unit area had ground cover, did not have paving, and was
not included in the fenced site of a residence, then it was designated
as open space.
Aerial Photography Interpretation
The grid overlay was centered at the Parque Independencia, the
hub of the commercial center of the city, and each cell of the grid was
given coordinates of longitude and latitude. These coordinates were
used to compare land use over the 27-year period between photographic
While the 1974 photographs were scaled to the 1973 city map, the
1948 aerial photography required scale adjustments before a land use
map could be compiled. The 1973 map of the city was photographically
reduced to accommodate the larger scale of the older aerial photographs.
The information was transferred to the 1973 city map. A final reduc-
tion of the map was accomplished in order to scale equally both land
use maps for the land use analysis. As in the case of the 1974 land
use data, each hectare cell was coded for coordinates and land use, and
the data were stored for computer-assisted comparison and evaluation.
A final determination of the city boundaries was accomplished
following the interpretation of the aerial photographic coverage and
compilation of the 1974 land use map containing the location of each
hectare of land use. One procedure would have involved connecting the
"outside" edges of all developed land and designating this line as the
city perimeter. The resulting boundary would have approximated the
executive proposal included in the presidential degree of 1975.
To have used these limits, however, would have excluded some develop-
ment that is of much interest but would have lain beyond the contigu-
ously built-up area.
Land speculation is an important influence on urban development
in the Caribbean. Land ownership and the economic advantages of keep-
ing land undeveloped as the city expands are common in an island
economy that tends to be inflationary. The land use map for 1974 in-
dicated that defining the city limits on the basis of contiguity of
developed land would have excluded significant expanses of residential
land, including the marginal housing identified at the edge of the
city, such as the communities of Katanga, Puerto Rico, Mandinga, and
Villa Faro. The solution was to determine the outside limits of built-
up area that was larger than five contiguous hectares in a particular.
land use category. All such developed land was connected at its out-
side edges to form the city boundary.
A field survey was undertaken in 1975 to characterize housing
conditions in the city. The urban area was too large to permit a com-
plete investigation of all housing, and, therefore, a stratified,
unaligned random sample of housing was conducted. The sampling design
included 10 percent of all streets involving nearly 150 streets rang-
ing from a single block to many blocks in length (Figure 4-3).
Avenida S. Bolivar was included in the sample, for instance, and this
major thoroughfare extends from the Parque Independencia to the western
edge of the city. The investigation of all housing along these streets
provided reliable information about the number and type of structures,
the land uses, building construction materials, indicators of socio-
economic status of the occupants of residences, the condition of
streets including curbing and sidewalks, traffic congestion, and pollu-
A key objection of the research was to determine land use,
especially residential land use, and it was assumed that, controlling
for the independent influences of such factors as socioeconomic status,
each newly arrived city inhabitant theoretically could find housing
anywhere within the urban confines. The mix of residents was presumed
to result from independent decisions related to income level, education,
employment, life-cycle stage, family size, marital status, and similar
situations in which people exhibiting similar socioeconomic status
aggregate. There are socioeconomic differences when comparing a hectare
of high-income residential land use in the city center with high-income
status in residential land use at the suburban fringe. This research
effort is at a more generalized level, however, and seeks to identify
gross distinctions between residential land use whicn would allow com-
parisons to be made between Anglo-American and Caribbean urban land use.
The urban area of Santo Domingo is generally subdivided into lots
of about one hectare. Land is sold in square-meter increments. The
colonial unit of measurement of one solare was slightly more than 100
meters and the old portions of the city reflect a subdivision pattern
of blocks 100 meters in length. It was decided that the hectare, 100
meters in length, would be the most efficient measurement unit for the
The sample size may be determined by estimating the population
parameters. For a degree of accuracy equal to 0.05 percent for one-
half of the normal curve, or a total interval width of 0.10, the
formula for estimating the population is
S 1.96 (o / /T).
0.10 = 1.96 o/ /N.
Solving for N, (1.96 01)2
N = (1.96 a / 0.1)
and a is to be estimated from the sample data. The estimate of the
standard error of the mean, a, is obtained from the Student's t distri-
bution. The degrees of freedom are since, for testing purposes, this
is nearly accurate. A level of confidence of 0.95 is acceptable; most
morphological research has had lower levels, and, although direction is
expected to be predictable, a two-tailed test will be used. Thus, at
0.95 confidence and a two-tailed test, the sample size will be
N = (1.96 8 / .1)2
N = ((1.96 x 1.96) / .1)2
N = 1,476.
The sample size would have to be 1,500 structures.
The mix of structures and land use in Santo Domingo is hetero-
geneous. A preliminary investigation of the city done by automobile
indicated that residential use was homogeneous on a block-by-block
basis, this regularity often continuing for many blocks along the
street. It is more efficient to use the stratified sampling proce-
dure where there appears to be greater homogeneity within than be-
tween aggregates (Harvey 1969, 352). Spatial sampling can include
random collection from an infinite number of points comprising the
area, or it can consist of a finite number of small area units which
make up the total.
The research includes sampling traverses that extended the full
length of any particular street sampled. Because of the linear trend
of development and of land use associated with the accessibility which
accompanies the networks of streets, pathways, and highways that dis-
sect the city, the stratified sample was based upon the city atlas pub-
lished by the National Police. A 10-percent random sample of more than
1,400 streets was drawn from the atlas. Each traverse was field sur-
veyed, structure by structure. The field survey measured 40 variables
including all structures, the external condition of the buildings, the
type of building materials used in walls and roofing, the number of
floors, the outward appearance including landscaping, evidence of
automobile use by the occupants, the additional activities of a com-
mercial or professional nature in a residence, the street conditions,
and whether the area exhibited congestion and deterioration. Each
block was determined by intersecting streets or the terminus and an
intersection. The information was recorded on tally sheets, similar to
Table 4-1, identified by the name of each intersecting street.
The purpose of the field survey was to group land use into five
general categories: residential, governmental, commercial, industrial,
and open,or underdeveloped. The residential land use category included
a seemingly endless assortment of housing types, especially in the
poorest areas of the city where almost any discarded materials would be
pressed into service as shelter. Apparently, building materials are
dependent upon the inventiveness of the occupants. Outside the
Table 4-1: Field Survey Instrument for Recording Land Use
and Building Conditions in Santo Domingo
Multiple Family ......... .
Commercial ...... ..........
industrial .... ............
Open Space ....................
Concrete .......... ......
Wood ... ..............
Palm ....... ........
Galvanized Steel Sheeting...
Galvanized Steel Sheeting..-
Asbestos ........ ..........
Yagua-Cana .. .......... .
Number of Floors
One . ..................
One and One-Half ............
Two ........ ............ .
Four ........ ................
Five or More ...............
Recently Painted .............
Carport .............. .....
Louvered Windows ...........
Grated Windows ...............
Fenced Property ..............
Curbing. .... ........... .
/ II I
r ry ~ i
r ~ --r'
marginal settlements, however, low-income persons tended to occupy long
wooden structures which housed four or more families, each household
possessing several rooms and a doorway facing the street. These
multiple-family structures contrasted with middle- and upper-income
apartments which more closely approximated those found in Anglo-
American cities. Whenever the structure varied from the single-family
residential home, it was necessary to determine its predominant use,
and this was accomplished by ruling out public, commercial, or indus-
trial activities, by interviewing the occupants, checking for multiple
mail boxes, listening for the sounds of playing children, looking for
drying laundry, observing pets roaming the hallways, and other manner
of information-gathering strategies.
Public housing was conspicuous for its uniformity. The national
government sponsored construction of urbanizaciones, or projects, which
were composed of housing types, e.g. "type A" or "type B." These were
blueprint structures that were found throughout the more recently devel-
oped sections of the city in public housing projects. Other middle-
income apartments were distinguished from tenements by their general
state of good repair and cleanliness, lack of open doorways and un-
employed, poorly dressed occupants, and absence of children, who were
assumed to be in school.
There was little difficulty in separating commercial from either
public/governmental or industrial use. In the downtown commercial cen-
ter, the main avenue was surveyed structure by structure on each floor,
and the dominant use noted. There were many structures in primarily
residential areas which included small stores or offices. Other
observations included whether there was evidence of fresh paint, an
indication of expenditures for upkeep which helps to distinguish low-
from middle-income housing. If, at the time of the survey of streets,
which occurred between 8:00 A.M. and 7:00 P.M., there were trucks and
buses passing along, if many cars were present, and if the consequent
noise made hearing normal conversation difficult, the street was deter-
mined to be congested at that site. The major avenues and main govern-
ment buildings in much of the commercial colonial center were often
congested. Heavy traffic and associated noise were prevalent in some
residential areas, as well, even in front of the private home of the
president of the republic.
Each of 140 streets was surveyed. The linear trend of this kind
of investigation introduces serial correlation. To control for the
regularity in the data, one-half of all data sites were randomly selec-
ted for the data analysis. The stratification allowed the number of
sites in each block to remain the same proportionally while minimizing
spatial auto-correlation (Harvey 1969, 363).
The field survey data for 40 nominal and ordinal scale variables
were stored in a computer by plotting the 140 streets on the city map,
overlaying the cell-grid system of hectares, and determining the loca-
tion of each site. Since the field data were collected and recorded
geographically, each site could be located on the city street network
between intersecting streets, in sequence, according to the order of
data collection. The surveyed sites could be readily assigned the
longitude and latitude of the grid overlay. However, where streets were
oblique to the grid, it was necessary to interpolate the location. The
location designation became the grid coordinates that were closest to
more than one-half of the sites lying between the recorded intersections.
The result was that all field sites were relegated to a total of 757 hec-
tares of land within the grid overlay. A simple algorithm was employed
to add another variable of distance from the cell center to an arbitrary
city focus at the Parque Independencia, where much urban activity is
Residential Land Use Definition of the Field Sample
Much of the developed land was residential, but the general ab-
sence of land use controls in the city resulted in mixed uses in the
field survey sites. A residential land use category would not be
obvious since it might range from strictly housing to only 14 percent
housing. The field investigation results required some criterion for
designating the predominant land use before progressing to the analysis
of the field results.
Limiting the residential land use designation to these field sur-
vey cells containing only homes would have been misleading since the
number of residential cells would have amounted to 333 out of the total
survey count of 757 cells. Where all the structures were residential,
44 percent of the surveyed city would be considered as residential.
Establishing a land use designation for each cell where there were
several uses present would have required determining the proportional
relationship and weighing the consequences of accepting a land use mix
that might fall somewhere within 14-99 percent (which represented the
range of the proportion of housing to other structures in a cell).
As the field survey data identified the number of structures by activ-
ity, it was possible to compute the percentage of total structures in
the hectare which were residential. There is no "correct" mixture
of land uses to guide one in assigning to each cell of the grid a par-
ticular land use category. The problem was to arrive at the most
reasonable proportion of residential use to other uses.
The proportion of residential to nonresidential structures in any
cell was determined by the following equations:
RES = Single Family + Multiple Family +
Apartment + Improvished Housing
RES% = (RES / (RES + INT + COM + IND)) (100)
The number of residential structures (RES) was the total of all housing
in a hectare cell. The percentage of residential land use within the
hectare (RES%) was calculated by dividing the total number of residen-
tial structures by all structures, including public (INT) and commercial
(COM) and industrial (IND) structures also found in the cell. The per-
centage conversion was obtained by multiplying the resulting proportion
Therefore, once the field survey cell was determined to be devel-
oped land, the proportion of residential sites to all sites within it
was used to arrive at a land use designation. Beginning with 14 per-
cent (the smallest proportion of residential to nonresidential struc-
tures in any hectare found to contain housing), increasing proportions
of residential to nonresidential structures were computed to determine
at what level most or all field-surveyed land would be included which
had some housing present in 1975. The field-survey cells were com-
pared with the 1974 aerial interpretation. Table 4-2 indicates the
results of the analysis. At a criterion of 25 percent residential,
658 hectares (or 87 percent) with some housing were in agreement.
.4 -' 4
= C. 0
a" 0 :
o a a a a a a
o 's o '
V- -v '2-
CDO J o 40
f I- i
- 2 P
03 ID CM ) if
0 0 CM n f
CNJ ioJ L
This assumes that housing growth over the nearly one year that elapsed
between the aerial coverage and the field sampling included the develop-
ment of open land for housing purposes. Such an assumption is not
unreasonable because of the rapid appearance of marginal housing. Just
one such settlement, Buenos Aires in the western extreme of the city,
is at least twice as large as the surveyed area of 658 hectares and
much of its growth occurred after 1968.
The 138 hectares which changed from nonresidential to residential
over the year amount to less than 2 percent of the urban area. If resi-
dential land area expanded at a rate to accommodate the exisitng
density, developed land area would have had to increase 5.94 square
kilometers over the year. But it is known that marginal settlements
absorb large numbers of newly arrived inhabitants. Furthermore, land
that may be designated other than residential can include large numbers
of residences. Thus, one hectare of land containing tens of small
shacks sheltering hundreds of people, crowded against a concrete wall
surrounding a huge mill, will be designated as industrial on the basis
Another 58 hectares were designated as residential in the field
sample but were interpreted as nonresidential. Undoubtedly, some of
these cells included instances of land clearance for other development
over the year that elapsed between the aerial reconnaissance and the
field survey. There is the presumption that interpretation error
occurred, that structures which appeared to be residential were not so
when examined in the field survey.
Land conversion was infrequent. The city population doubled in
each of the post-World War II decades, a rate exceeding 6 percent since
1950 (Durand and Paldez 1965, 179; World Bank 1972, 185). There is
little vertical construction. The city area expanded at a continuous
annual rate of 6.5 percent over the 1948-1975 period. The built-up
area increased over 400 percent, from 17.09 square kilometers (10.62
square miles) to 91.45 square kilometers (56.82 square miles). Much
of this expansion occurred during the rapid economic growth period that
followed the end of the 1965 civil war.
The 58 hectares were grouped into 15 hectares of industrial use,
8 hectares of commercial use, and 35 hectares of open space. Over 60
percent of the area in disagreement was undeveloped at the time of the
field survey. The proportion of open space to other land uses as
determined in the aerial interpretation is about the same, suggesting
a consistent error in the interpretation.
The largest group of cells in disagreement, open space versus
residential, was analyzed. Most of the interpretation errors were
among cells that had middle- and high-income residential use. Thus,
the higher the income level of the occupants, the more often the field
survey indicated that the land was undeveloped. This raised the
question of whether interpretation errors were due to the low density
of the higher income, residential land use which made distinguishing
between the two uses more difficult. Mapping all 58 cells did not
reveal patterns that would suggest another explanation for the dis-
agreement between the two data sources.
Another 187 hectares of land were interpreted as residential and
found to have varying degrees of nonresidential use interspersed with
housing. The analysis of these cells indicated that over 80 percent of
the nonresidential use was commercial, followed by 16 percent institu-
tional, and 2 percent industrial. Experience in the field indicated
that where the land use mix was often residential, commercial use was
usually corner convenience stores.
Based upon the comparison of the two data bases, Table 4-2 indi-
cates that 520 hectares had some housing and were designated as resi-
dential as a result of the aerial photography interpretation. There-
fore, over 90 percent of the land common to the two data sources was
in agreement as to land use. In 333 hectares, there was no other use
indicated other than residential.
A comparison of the aerial photography and field data was made in
order to ascertain the degree of confidence that could be placed upon
the residential classification. Because the sample size is quite
large, the central limit theorem applies where the distribution of the
sample means approaches normality. The text of proportions can be seen
as a special instance of such means, involving a simple, dichotomized,
nominal-scale sample. By assigning a value of one to residential cells,
and zero to nonresidential cells, the scores can be treated as an
interval scale not requiring the determination of the exact difference
between the degree of residential versus nonresidential treatment.
Because all cells are concentrated into a bimodal distribution, normal-
ity is not present; however, with the large sample size, the distribu-
tion of sample means will be approximately normal. The mean of this
population of values of one or zero is their sum divided by the total
number of cells. The number of residential cells is the total number
of cells multiplied by the proportion that are residential.
With the use of the 50-percent criterion for designating residen-
tial land use (where there was a land use mix of housing and other
activities within the cell), there were 739 hectares included in the
analysis. Of these, 45 percent were entirely residential in both data
sources; 179 hectares were interpreted as residential in the aerial
photography but found to have a mixture of uses in the field survey.
Fifty-eight cells were nonresidential in the field survey but residen-
tial in the interpretation. Another 130 cells were just the opposite,
i.e. nonresidential in the photography and residential in the field
survey. Thus, out of the total sample size of 739 cells, 333 plus 179,
or 512 cells, could be classified as residential in both data bases.
The initial hypothesis, that no significant differences existed between
the population proportion of residential cells and the sample propor-
tion of residential land use, was tested.
The test was the single sample of proportion. The test statistic,
the Z score, is computed from the formula
Z = (ps-q u / vPuqTu/
where the proportion of residential hectares in the aerial interpreta-
tion is pu, the remaining proportion of cells is qu, and the proportion
of area in housing in the field survey is p s
The Z score for the proportion of residential cells that were in
agreement in both data sources and were entirely residential was not
significant at the .01 level for a critical region of a one-tailed test.
The initial hypothesis that there were no significant differences of
proportion was not rejected. The possibility that other percentages
of housing to nonresidential structures in a hectare were significant
remained to be tested.
Beginning with 95 percent and decreasing at 5-percent intervals,
the other proportions were tested. At the 85-percent level, the test
was significant; the difference of proportions between the sample sur-
vey and the aerial photography was great enough to conclude that it
was probable that land found to be residential in 1974 would not be com-
pletely residential in the next year.
Most land use studies of Anglo-American cities have concluded that
residential land use is approximately one-half of the total developed
urban space. Where suburbanization has been a long-term occurrence,
land use sorting will have reduced housing in the center city which is
replaced by nonresidential uses. The suburban cities, on the other hand,
contain higher proportions of residential land use.
In Santo Domingo where land use controls are weak or nonexistent,
the proportion of residential to nonresidential use should be lower.
A wide dispersal of housing in heterogeneous communities is more likely,
and unless the suburbanization process has been a significant influence,
there should be few exclusively residential areas.
The 50-percent criterion included 87 percent of field survey cells.
Most of the sample is included in the analysis: 739 of the 757 sur-
veyed cells. Choosing a lower proportion would have expanded the number
of residential cells only slightly while including those that would
obviously be better classified as commercial, industrial, or another
nonresidential use. At a higher proportion, too many cells would be
excluded from consideration in the analysis.
The 50-percent criterion for the minimum proportion of housing
to nonresidential structures in a cell became the basis for tabulating
averages. Each field variable was summed for all cells, and an average,
median, and range of values were calculated based upon the sample size
of 739 hectares.
Both the concentric zone and sector models of urban change empha-
size residential land use. In order to test the probability that one
configuration was more applicable to Santo Domingo's growth, it was nec-
essary first to delimit probable zones and sectors of homogeneous resi-
dential land use. This required an examination of the 1948 and 1974
land uses and transportation networks to determine the areas of greatest
discontinuity of activities where zone and sector limits would be
TESTING URBAN ECOLOGICAL THEORY
Allocating Zone and Sector Location
If the city experienced succeeding waves of growth radiating out-
ward from a central business district, then Santo Domingo's housing
would exhibit some aggregation into zones in which the within-zone
variation in housing type would be less than that between zones. The
Park-Burgess concentric zone model suggests a socioeconomic gradient of
housing with the poor located near the CBD and in a transition zone
containing tenements and other low-income rentals. Farther from the
center of the city are middle-income homes which are superceded by high-
income residences as the distance from the central business district
increases. Santo Domingo's residential land use does not resemble the
ideal model, however, since it is sited at the Caribbean coast which
has prevented the complete evolution of a circular pattern.
The land use data analysis confirmed the clustering of both low-
and high-income housing and dispersal of medium-income housing. There-
fore, utilizing an average distance for each type of housing would not
delimit the probable zones. A comparison of land use over the 28-
year period, shown in Figure 5-1, revealed that the least change in
land use was concentrated at approximately 1,000 and 2,500 meters from
the city center established at the Parque Independencia. Concentric
zone theory would argue that the boundary areas between zones would
1000 2000 3000 4000 5000 6000
Figure 5-1: Frequency in Hectares, of Stable Land Use, 1948-
1975, by Distance from the City Center
experience greatest instability. For Santo Domingo, then, the zonal
boundaries would be indicated between the stable modes. The inner
limit of the first zone was established at 1,000 meters, and it was
assumed that low-cost housing lay beyond a radius of 1,750 meters from
the CBD, or one-half of the distance between this and the other stable
As Table 5-1 shows, 542 meters separated the average distances
for medium- and high-income housing. One-half of the distance, 271
meters, was added to the average distance of high-income housing, 4,741
meters from the city center, and this distance of 5,022 meters was desig-
nated the boundary between high- and medium-income residential land use.
The boundary between low- and high-cost housing was one-half the dis-
tance from this to the inner limit of low-income housing. All that
remained was to establish a maximum extent of the outward reach of resi-
dential land use. Since the open land averaged 7,000 meters distant
from the CBD, medium-cost housing was extended approximately 1,700 meters
to equal the distance arrived at between the boundaries of low and
The final zone configuration is shown in Figure 5-2. The zones,
including their ranges, are
Zone 1 Other land use, 0 to 1,674 meters;
Zone 2 Low-cost residential land use, 1,675 to 3,348 meters;
Zone 3 High-cost residential land use, 3,349 to 5,022 meters;
Zone 4 Medium-cost residential land use, 5,023 to 6,696 meters;
Zone 5 Open land use, 6,697 to 11,700 meters, at the western
extreme of the city.
0. C o C: LO C, CM
S- Ol M C -
2 CM CO CM~ -
a) CO OCM m -
00 C C, CD
a) l li L C
u4' M a) CO m C) m
~C CO 1 CO r'u C M
EI CM C M C
a)C CMCI ~ CM CO CM M
u Z 10 C0 C1 C aC) M CD C
I a) C') CM CM C- M C
ON CM CD
10 10 S- X E2 0 S-
a4- a) a) aO CM a a)
SM M 41 S- 4M C
Ia) C a0 c' M C' C a)
It- CM a) -- .-M
a) cu ()u 4 a) a)
cu CU 0) cm 0)< O li a) 0)- cm
c -a 4l s) ma) a) 4-' a) a)
CoC1/ >) E- (U 4' -
a) a) (CC C-- -, a)C ) C
c) a) ar) (C C- a) a) a
~L CL ~L
Establishing sectors was less complex. Hoyt hypothesized that
sector boundaries, influenced by topography and evidenced in the loca-
tion of major transportation-communication corridors, continue to grow
with outward expansion of the city. Growth of residential neighbor-
hoods became dependent upon the corridors for continued accessibility
to central business district activities. McElrath's (1962) study in-
corporated 10 sectors which were found to be too many. Johnston (1971,
334) concluded that linear gradient change as evidenced in within-zone
heterogeneity was best controlled utilizing only a few sectors.
Both the land use and the city maps, as well as the field experi-
ence, suggested that six sectors would be needed to differentiate land
use sufficiently to test the applicability of the sector model. These
six, bounded by the coastline, the river, the limestone terraces, and
the major avenues, are as follows (Figure 5-2):
Sector 1 Caribbean Sea and Avenue J. Contreras;
Sector 2 Avenue J. Contreras and Avenue S. Bolivar;
Sector 3 Avenue S. Bolivar and Avenue S. Martin;
Sector 4 Avenue S. Martin and Avenue J. Duarte;
Sector 5 Avenue J. Duarte and the Ozama River;
Sector 6 Ozama River and the Caribbean Sea.
The least elevational change is found in Sector 1. The second sector
rises from 10 to 25 meters, while Sector 3 has the highest elevation
found along the limestone terraces extending east to west parallel to
the sea. The remaining sectors, 4, 5, and 6, range from 50 meters to
sea level and include steeply sloping land in the deep arroyos in the
northwest corner of the city, along the riverbanks,and at the seacoast.
The two model configurations were superimposed on the 1948 and 1974
land use maps. Every hectare was assigned both a zone and sector designa-
tion; thus, any cell of land as determined in the 1974 land use mapping
was given a location in the grid, and all other cell characteristics were
associated by this location variable. Many of the land use cells com-
prised the five zones which crossed all the sector boundaries. Most of
the sectors contained portions of all five zones.
Testing the Models of Land Use Change
In the assessment of the zone and sector models, the residential
land use determined by aerial interpretation represented the population
of all such land use in the two base years. The field survey of 10 per-
cent of all land use in the city included 739 of the 9,145 hectares of
urban land. A merge by cell of two data bases resulted in the selec-
tion of 512 hectares established as residential in the 1974 aerial photog-
raphy and having at least 50-percent residential in the field survey.
The allocation of every hectare in the city to one of five concentric
zones and six sectors meant that each hectare of urban land could be
given scores for its location in both a zone and sector.
Total residential land use in the 1975 field survey data base was
sufficiently large, at 512 hectares, to be tested as representative of the
entire city. The 512 hectares were 12 percent of the 1974 residential
land area. The field survey information was grouped into low-, medium-,
and high-income land use as established by the aerial interpretation,
and the frequencies were recorded in a matrix of land use type (Table
5-2). The zones were the rows and the sectors were the column figures
in the initial 5 x 6 matrices for each of the three residential land use
Table 5-2: Frequency Matrix of Field Survey, 50-Percent Criterion, for
Zone and Section Models, by Residential Land Use Type
Zones 1 2 3 4 5 6 Totals
1 3 0 0 2 5 7 17
2 0 0 0 26 18 29 73
Low-Income 3 0 0 1 19 43 38 101
4 0 4 3 0 0 6 13
5 4 0 19 0 0 0 23
Totals 7 4 23 47 66 80 227
1 10 0 0 1 0 0 11
2 5 2 4 3 14 12 40
Medium-Income 3 4 0 5 8 5 21 43
4 12 3 4 0 0 5 24
5 7 40 33 0 0 0 80
Totals 38 45 46 12 19 38 198
1 12 9 7 5 0 0 33
2 9 3 5 0 0 0 17
High-Income 3 0 2 11 0 0 0 13
4 1 2 4 2 0 0 9
5 5 6 1 2 0 0 14
Totals 27 22 28 9 0 0 86
The chi-square test is a general procedure that can be used to
evaluate whether these frequencies of grouped, empirically collected
data differ significantly from expected frequencies. Several assump-
tions were involved. These included random sampling, independent selec-
tion, and equal proportions. Expected frequencies were calculated
for each contingency problem involving a land use type. The resulting
matrices are given in Table 5-3.
Since housing sites can range from very small toall-inclusive
plots within a hectare and theoretically could encompass an entire zone
or sector, any matrix cell could have a wide range of possible values.
However, since land development tends to reflect a much more limited
range, the cell frequencies are whole numbers of low value, the result
of a measurement unit that forced a single land use cell designation.
A random sorting of the field data would result in a matrix of 30 cells
in which all land would be evenly distributed. Deviation from the
expected frequencies was tested using the chi-square test of signifi-
cance. Its use required a correction for continuity in order to ensure
that the sampling distribution approximates the sampling distribution of
the chi-square table. Generally, the fewer the number of matrix cells
and more nearly equal the marginal totals, the smaller the sample size
must be, but whenever any of the expected frequencies is less than six,
it becomes necessary to make some adjustment (Blalock 1972, 285-286;
Taylor 1977, 110). In practice, such an adjustment involves combining
categories in a rational manner in order to reduce the number of matrix
cells by combining where frequencies number less than six. Rather than
exclude field data and in consideration of the influence that topography
Table 5-3: Expected Frequency Matrices for Field Data, 50-Per-
cent Criterion, for Zone and Sector Models, by
Residential Land Use