People are not distributed randomly within an urban area. They concentrate in particular neighborhoods, depending on their social characteristics. Geographers describe where different types of people are likely to live within an urban area, and they offer explanations for why these patterns occur.
Models of Urban Structure Sociologists, economists, and geographers have developed three models to help explain where different types of people tend to live in an urban area—the concentric zone, sector, and multiple nuclei models. The peripheral model is a modification of the multiple nuclei model. The three models have been applied to cities in the United States and in other countries with varying levels of success.
Concentric Zone Model The concentric zone model, created in 1923 by sociologist E.W. Burgess, was the first model to explain the distribution of different social groups within urban areas. According to the concentric zone model, a city grows outward from a central area in a series of concentric rings, like growth rings of a tree. The precise size and width of the rings vary from one city to another, but the same basic types of rings appear in the same order.
Sector Model In the sector model, developed in 1939 by land economist Homer Hoyt, the city develops in a series of sectors, not rings. Certain areas of the city are more attractive for various activities, originally because of an environmental consideration or even by mere chance. Once a district with high-class housing is established, the most expensive new housing is built on the outer edge of that district, farther out from the center. The best housing is therefore found in a corridor extending from downtown to the outer edge of the city.
Multiple Nuclei & Galactic Models According to the multiple nuclei model, developed by geographers C.D. Harris and E.L. Ullman in 1945, a city is a complex structure that includes more than one center around which activities revolve. Examples of these nodes include a port, a neighborhood business center, a university, an airport, and a park. The multiple nuclei theory states that some activities are attracted to particular nodes, whereas others try to avoid them. Heavy industry and high-class housing rarely exist in the same neighborhood. According to the galactic (or peripheral) model developed by Harris in 1960, an urban area consists of an inner city surrounded by large suburban residential and service nodes tied together by a beltway or ring road. The nodes of consumer and business services around the beltway are called edge cities.
Applying the Models in North America The three models of urban structure help us understand where people with different social characteristics tend to live within an urban area.
Social Area Analysis The study of where people of varying living standards, ethnic backgrounds, and lifestyles live within an urban area is social area analysis. Urban areas in the United States are divided into census tracts that each contain approximately 5,000 residents and correspond, where possible, to neighborhood boundaries. Each decade the U.S. Bureau of the Census publishes data summarizing the characteristics of the residents and housing in each tract. Social scientists can use social area analysis to compare the distribution of characteristics and create an overall picture of where various types of people tend to live.
Social Area Analysis: Concentric Zones In this model two households with the same ethnicity and income are compared. The household in the newly constructed home is more likely to live in the outer ring. In comparison, the older home is more likely to be located in the inner ring.
Social Area Analysis: Sectors Household distribution patterns in the sector model show that households with high incomes are unlikely to live in the same sector as households with lower incomes.
Social Area Analysis: Nuclei In this analysis people with the same ethnic or racial background are likely to live near each other.
Limitations of the Models None of the three models taken individually completely explains why different types of people live in distinctive parts of a city. Critics view the models as too simple and fail to consider the variety of reasons that lead people to select particular residential locations. Because the three models are all based on conditions that existed in U.S. cities between the two world wars, critics also question their relevance to contemporary urban patterns in the United States or in other countries.
Structure of European Cities American urban areas differ from those elsewhere in the world. These differences do not invalidate the three models of internal urban structure, but they do point out that social groups in other countries may not have the same reasons for selecting particular neighborhoods within their cities.
CBDs in Europe Europe’s CBDs have a different mix of land uses than those in North America. Differences stem from the medieval origins of many of Europe’s CBDs. European cities display a legacy of low-rise structures and narrow streets, built as long ago as medieval times. Differences include residences, consumer services, and public services.
· Residences—more people live downtown in cities outside of North America.
· Consumer services—more people live in Europe’s CBDs in part because they are attracted to the concentration of consumer services, such as cultural activities and animated nightlife.
· Public services—the most prominent structures in Europe’s CBDs are often public and semipublic services, such as churches and former royal palaces, situated on the most important public squares.
· Business services—Europe’s CBDs contain professional and financial services. However, business services in Europe’s CBDs are less likely to be housed in skyscrapers than those in North America.
Concentric Zones in Europe As in U.S. urban areas, the newer housing in the Paris region is clustered in its outer rings, and the older housing is closer to the center. Unlike in U.S. urban areas, much of the newer suburban housing is in high-rise apartments rather than single-family homes.
Sectors in Europe Similar to U.S. urban areas, higher-income people cluster in a southwest sector in the Paris region. This preference has its roots in the Industrial Revolution when factories were built in the north and east.
Multiple Nuclei in Europe. European urban areas, including Paris, have experienced a large increase in immigration from other regions of the world. In contrast to U.S. urban areas, most ethnic and racial minorities reside in the suburbs of Paris.
Premodern Cities in Developing Countries Cities in developing countries may date from ancient times. For most of recorded history, the world’s largest cities have been in Asia. However, until modern times, most Asians lived in rural settlements. The ancient and medieval structure of these cities was influenced by the cultural values of the indigenous peoples living there.
Ancient & Medieval City: Beijing Archaeological evidence of Beijing dates from 1045 B.C.E., although the city may have been founded thousands of years earlier. A succession of invaders and dynasties shaped what is now the central area of Beijing.
Beijing During the Yuan Dynasty Beginning in 1267, Kublai Khan, founder of the Yuan Dynasty, constructed a new city called Dadu. Three palaces were built in the heart of Dadu, two housing the imperial family, and the other offices. Residential areas were laid out in a checkerboard pattern divided by wider roads and narrower alleys. Three markets were placed in the residential areas. An outer wall surrounded the residential areas, and an inner wall surrounded the palaces.
Beijing During the Ming Dynasty After capturing Dadu in 1368, the Ming dynasty reconstructed it over the next several decades. The imperial palace was demolished and replaced with new structures, including the Forbidden City and the Temple of Heaven. The city was then called Beijing.
Colonial Legacy When Europeans gained control of much of Africa, Asia, and Latin America, their colonial policies left an indelible mark on many cities. One feature of European control was the imposition of standardized plans for cities. For example, all Spanish cities in Latin America were built according to the Laws of the Indies, drafted in 1573. The laws explicitly outlined how colonial cities were to be constructed. In some places, European colonial powers built a new city next to the existing one. The new city was the location for colonial services, such as administration, military command, and international trade, as well as housing for European colonists. In other cases, European colonial powers simply demolished the precolonial city.
Applying the Models in Developing Countries The three models of urban structure described earlier in this chapter help to explain contemporary patterns within the urban areas in developing countries. Rapid growth of population and land area has strengthened the applicability of the models in some cities, but reduced their usefulness in other instances.
Concentric Zones in Developing Countries The concentric zone model has been used to examine cities in developing countries most frequently. A notable example is geographer Harm deBlij’s model of sub-Saharan African cities. The inner rings are inhabited by people with higher-incomes. These inner rings have the most attractive residential areas due to proximity to businesses and consumer services. These inner rings also offer vital public services, such as water, electricity, paved roads, and garbage pickup. As cities grow rapidly in developing countries, rings are constantly being added on the periphery to accommodate immigrants from rural areas attracted by job opportunities. Many residential areas in the outer rings take the form of informal settlements, also known as squatter settlements. The United Nations has identified an informal settlement as a residential area where housing has been built on land to which the occupants have no legal claim or has not been built to the city’s standard for legal buildings. Informal settlements have few services because neither the city nor the residents can afford them. Informal settlements have a variety of names such as barriadas and favelas in Latin America, bastes in India, and barong-barong in the Philippines.
Sectors in Developing Countries Geographers Ernest Griffin and Larry Ford show that in Latin American cities, wealthy people push out from the center in a well-defined elite residential sector. The elite sector forms on either side of a narrow spine that contains offices, shops, and amenities attractive to wealthy people, such as restaurants, theaters, parks, and zoos. The wealthy are also attracted to the center and spine because services such as water and electricity are more readily available and reliable there than elsewhere. Wealthy and middle-class residents avoid living near sectors of “disamenity”, which are land uses that may be noisy or polluting or that cater to low-income residents.
Multiple Nuclei in Developing Countries Cities in some developing countries show evidence of the multiple nuclei model by containing a complex mix of ethnic groups. T.G. McGee’s model of a Southeast Asian city superimposes on concentric zones several nodes of squatter settlements and what he called “alien” zones, where foreigners, usually Chinese, live and work. McGee found that Southeast Asian cities do not typically have a strong CBD. Instead, the various functions of the CBD are dispersed to several nodes.
Changing Urban Structure of Mexico City Mexico City provides an example of a city in a developing country that has passed through three stages of development: pre-European origin, the European colonial period, and postcolonial independence. The modern city also displays evidence of the models of urban structure.
Precolonial Mexico City The Aztecs founded Mexico City—which the called Tenochtitlán—on a hill known as Chapultepec (“the hill of the grasshopper”). They eventually moved their settlement to a 10-square-kilometer island in Lake Texcoco in 1325. The node of religious life was the Great Temple. Most food, merchandise, and building materials crossed from the mainland to the island by boat, and the island was laced with canals to facilitate movement. As the Aztecs conquered neighboring populations over the following two centuries, Tenochtitlán grew to a population of a half-million.
Colonial Mexico City The Spanish conquered Tenochtitlán in 1521 after a two-year siege. They destroyed Tenochtitlán, dispersed or killed most of the inhabitants, and constructed a new city on the site. The Spanish built Mexico City around a main square, called the Zócalo, on the site of the Aztecs’ sacred precinct in the center of the island. Streets were laid out in a grid pattern extending from the Zócalo.
Mexico City Since Independence At independence, Mexico City was a relatively small city. The population grew modestly during the nineteenth century, reaching around 500,000 in 1900. The population grew dramatically during the twentieth century, to 3 million in 1950, and 21 million in the urban area in 2018. Millions have migrated to the cities in search of work. In 1903, most of Lake Texcoco was drained by a gigantic canal and tunnel project, allowing the city to expand to the north and east.
13.2
African City Model Also called the De Blij Model most African cities are under forty percent urbanized. Africa has some of the world’s fastest growing cities, and the impact that European Colonialism is clearly evident.
Brownfields a former industrial or commercial site that people perceive to be contaminated environmentally
Burgess concentric-zone model A model of the internal structure of cities in which social groups are spatially arranged in a series of rings.
Census tract An area delineated by the U.S. Bureau of the Census for which statistics are published; in urban areas, census tracts correspond roughly to neighborhoods.
Christaller's central place theory A theory that explains the distribution of services based on the fact that settlements serve as centers of market areas for services; larger settlements are fewer and farther apart than smaller settlements and provide services for a larger number of people who are willing to travel farther. A market center for the exchange of services by people attracted from the surrounding area.
Consumer service A business that provides services primarily to individual consumers, including retail services and education, health, and leisure services.
Disamenity zone the very poorest parts of cities that in extreme cases are not even connected to city services (amenities) and are controlled by gangs and drugs (Favelas in Rio).
Edge city a relatively large urban area situated on the outskirts of a city, typically beside a major road. A node of office and retail activities on the edge of an urban area.
Galactic city model A model of North American urban areas consisting of an inner city surrounded by large suburban residential and business areas tied together by a beltway or ring road.
Harris and Ullman multiple nuclei model A model of the internal structure of cities in which social groups are arranged around a collection of nodes of activities.
Hoyt sector model A model of the internal structure of cities in which social groups are arranged around a series of sectors, or wedges, radiating out from the central business district.
Informal settlement An area within a city in a less developed country in which people illegally establish residences on land they do not own or rent and erect homemade structures.
Latin American city model combines elements of Latin American Culture and globalization by combining radial sectors and concentric zones. Includes a thriving CBD with a commercial spine. The quality of houses decreases as one moves outward away from the CBD, and the areas of worse housing occurs in the disamenity sectors.
Market area (or hinterland) geographic zone containing the people who are likely to purchase a firm's goods or services
Periodic market A collection of individual vendors who come together to offer goods and services in a location on specified days.
Slum a heavily populated area of a city where poor resident live in substandard homes
Social area analysis Statistical analysis used to identify where people of similar living standards, ethnic background, and lifestyle live within an urban area.
Southeast Asian city model McGee Model features middle-income housing in suburban areas. This reflects the larger percentage of middle-class citizens No formal central business district (CBD)
Squatter settlement groups of house made out of cheap, non-traditional materials built on land not owned by the residents
Urbanization population shift from rural to urban areas
Zone of abandonment areas or neighborhoods where most people migrate away often due to lack of jobs