MODELS OF URBAN STRUCTURE GROUNDING People are not randomly distributed in an urban area. Instead, they concentrate in particular neighborhoods by social characteristics. Geographers have developed three models to explain where different types of people will live in urban areas: THE CONCENTRIC ZONE MODEL THE SECTOR MODEL THE MULTIPLE NUCLEI MODEL The models were developed based on Chicago (a very flat city on a fairly uniform prairie, and then adapted to other cities. CONCENTRIC ZONE MODEL (THE BURGESS MODEL) HISTORY The model was developed by EW Burgess in 1923, and is VERY SIMILAR to VON THUNEN’S MODEL for agricultural land use from chapter 10. THE MODEL A city grows outwards in concentric rings from a central area (the size and width of the ring varies by city). There are five rings: 1. CBD: nonresidential activities concentrate here 2. Zone in Transition: industry, poor quality housing, immigrants living in subdivided apartments, rooming houses for singles 3. Zone of Independent Workers Homes: working-class homes (modest, older homes with stable, working-class families) 4. Zone of better residences: newer, more spacious homes for middle-class families 5. Commuter’s Zone: small villages that are dormitory towns for some CBD workers BURGESS AND VON THUNEN’s MODELS BURGESS Model describes urban/city land use relative to the CBD VON THUNEN Model describes agricultural/rural land use relative to the settlement Both Models assume: --land of uniform character and features --the importance of centrality/accessibility to the market --that individuals will maximize profit/land use and minimize costs --that transportation costs are uniformly proportional to distance in all directions --A single market Location affects land use: 1. Intensive land use near CBD because of the high cost of rent 2. Intensity/density of residential land use decreases with distance from CBD because households and other land uses locate further from CBD and can afford transportation 3. High socioeconomic class at periphery because families can afford larger homes/acreage/transportation Location affects land use: 1. Intensive land use near market because farmers need high profits to pay rent 2. Wood and perishable products near the market because they need frequent/brief transportation to market 3. Extensive agriculture at the periphery because of the low land rent, transportation costs and less perishable food products SECTOR MODEL (THE HOYT MODEL) HISTORY The model was developed by HOMER HOYT in 1939. THE MODEL A city develops in a series of sectors because certain areas of the city are more attractive for certain activities. As the city develops, the activity expands outwards in a wedge (sector) from the center as new facilities for that activity are added to the outer edge of the original sector. The Model also has five types of sectors (see above). MULTIPLE NUCLEI MODEL (THE HARRIS-ULLMAN MODEL) HISTORY The model was developed by CD HARRIS and EL ULLMAN in 1939. THE MODEL A city is a complex structure that includes more than one center around which activities revolve (ex: a port, neighborhood business center, airport, park, university, etc.) A given node is a pull for some activity but a push for another. For example, high-income housing will not be pulled by an industrial node. APPLYING THE MODELS Urban structure models explain both where and why people with given social characteristics live in an urban area. Effective application of the models depends on getting good data on the scale on individual neighborhoods Good demographic data comes from taking a census. The US census bureau breaks urban areas into CENSUS TRACTS where each tract will comprise about 5000 people and correspond (if possible) to neighborhood boundaries. Chattanooga Census Tract Map The census collects data on dozens of demographic characteristics which can then be plotted on a map to show the distributions (and patterns) of various characteristics over space. (See Every City, Every Block) Taken separately, none of the models are adequate explanations for contemporary urban patterns. However, when combined, they can begin to create an accurate picture of settlement. EX: Two families of same income and ethnicity, but one owns and one rents. What would CZM predict? Two families who own their own home but have different incomes. What would SM predict? CONCENTRIC ZONE 1. CBD 2. Zone in Transition 3. Zone of Ind. Workers Homes 4. Zone of better residences 5. Commuter’s Zone SECTOR 1. CBD 2. Transportation and Industry 3. Low-class residential 4. Middle-class residential 5. High-class residential MULTIPLE NUCLEI 1. CBD 2. Wholesale, light manufacturing 3. Low- 4. Medium- 5. High- (Class Residential) 6. Heavy Manufacturing 7. Outlying BD 8. Residential- 9. Industrial- (Suburb) APPLYING THE MODELS Dallas: PERCENTAGE OF HOME OWNERS Dallas: HIGH-INCOME HOUSEHOLDS Dallas: DISTRIBUTION OF MINORITIES As the concentric Zone model predicts, the percentage of owner-occupied homes is greater in outer rings of the city. As the sector model predicts, the highestincome homes extend in a single sector to the north of the CBD As the multiple nuclei model predicts, African Americans and Hispanics mostly occupy separate nodes to the south and west of the CBD respectively. EUROPEAN CITIES American urban areas differ from those in other countries (both MDCs and LDCs) around the world. The differences do not invalidate the models but show that social groups have different reasons for choosing their neighborhoods in another culture. DISTINCTIONS Wealthy Europeans still live in inner rings of the upper-class sector, not just in suburbs (access to shops and restored, historic residence) Low-income Europeans are FAR LESS likely to live in inner-city neighborhoods and more likely to live in suburbs (longer commutes, poorer schools-shopsservices, higher levels of crime-violence-drugs, no yards) Ethnic minorities are clustered in suburbs European officials encouraged construction of highdensity suburbs to preserve greenspaces and to minimize sprawl SIMILARITIES Wealthy Europeans do cluster in a single sector extending from the CBD (usually high ground and near palaces) LESS DEVELOPED COUNTRIES European colonial policies left a heavy mark on the development of many LDC cities. For example, the poor are concentrated in suburbs, and wealthy families live near city centers and in a sector extending from the center. Many LDC cities have passed through three stages of development: PRE-COLONIAL CITIES Few cities existed in Africa, Asia and Latin America before Europeans established colonies (most lived in rural settlements). Many cities were built surrounding a religious core. Latin America: Mexico and Andean Highlands Africa: Nile Valley, Islamic Empires in North & East Asia: South and East (esp. India, China, Japan) TENOCHTITLAN appears at right FEZ, Morocco ISLAMIC CITIES --Centers were religious and marketplaces --Gov buildings/wealthy homes surrounded center --Lower wealth/status families farther from core --recent immigrants on outskirts --Commerce in concentric, hierarchical pattern COLONIAL CITIES CITIES SINCE INDEPENDENCE As Europeans gained control of colonies, they expanded existing cities to provide colonial services. Since independence, as LDC cities begin to industrialize, millions of people have flocked to cities looking for work. The pre-existing city was either: A) demolished (the Spanish destroyed Tenochtitlan in 1521 and built Mexico City) OR B) left to one side with the expansion happening in a new area (the French in Morocco, the British in New Delhi). Wealthy families push out from center in a welldefined sector on either spine of a high-end service sector SQUATTER SETTLEMENTS LDC cities are unable to house the rapidly growing number of urban poor. Most poor immigrants to urban areas live in SQUATTER SETTLEMENTS (large, unplanned neighborhoods on the outskirts of LDC cities… aka favelas [Latin America], bidonvilles [North Africa], bastees [India], gecekondu [Turkey], kampongs [Malaysia], barong-barong [Phillippines]. RIO DE JANEIRO WHY THEY FORM --Large scale rural to urban migration (looking for jobs) --Poor citizens who cannot afford planned housing --Lack of enough housing (public and private) --Lack of (failure to enforce) land use policy LOCATION -- On edge/periphery of the city. --On otherwise unusable/undersirable land (ravines, gullies, hillsides, floodplains, landfills, cemeteries, industrial zones) --On Land with an unclear title CHARACTERISTICS --Unplanned streets and shelters/homes are constructed of scrap --Have few to no services --Lack schools, paved roads, telephones, sewers, running water --SOME have high levels of violence Video on Rocinha in Brazil CONSEQUENCES --Unhealthy conditions lead to high morbidity and mortality --Increase in crime --Development of gangs or other extralegal authority systems --Development of political action/unrest --Increased water pollution due to lack of sanitation and garbage removal --Increased soil erosion on hillsides and deforestation --Decreased air quality from wood fires for heating and cooking --Increase in availability of cheap labor --Increased risk of disasters(fires, industrial accidents, mudslides, flooding) --Strain on infrastructure with burden on tax payers SQUATTER SETTLEMENTS Favelas in Rio de Janeiro, Brazil SQUATTER SETTLEMENTS AND SUBURBS Both squatter settlements and suburbs reflect growth of urban areas (URBANIZATION). Both are a type of SPRAWL (the unplanned extension of urban land uses into rural areas). (CNN Sprawl site) REGIONS DEFINING CHARACTERISTICS REASONS DEMOGRAPHIC TRANSITION --Suburbs in MDCs and more developed pockets of some LDCs. --Suburbs are planned developments. They are added to the outer edge of settlements (usually on prime land). They are equipped with a full range of public and consumer services. They are occupied by higher income families. The residents are often more established/longterm residents. -- Wealthy urban dwellers leave the inner parts of the city, or first ring suburbs, in order to have more open space, larger homes, or easier access to employment outside the center. -- As countries enter stage 3 of the DT, residents who have gained sufficient wealth engage in intraregional migration at the scale of cities moving from central city neighborhoods to suburban areas. --Squatter Settlements in LDCs --Squatter settlements are unplanned developments. They are added to the outer edge of settlements (usually on unused/unwanted land). They have no public services and few consumer services. They are occupied by the lowest income families. The residents are often recent immigrants to the area. --Poor people from the countryside move to the city but, unable to afford homes in the center, establish themselves on the periphery. Eventually, they will seek services from the city and have roads, schools, etc. --As countries enter stage 2 of the DT and begin to industrialize, farmers from rural areas move to cities seeking factory work, OR jobless people from stage 2 countries migrate to economic centers of stage 3 countries (often to primate cities) to seek jobs.