Getting Started
Why is the most expensive real estate often found in the center of a city? Why are certain neighborhoods associated with specific industries or income levels? Cities are not random collections of buildings and people; they have a distinct internal structure. Geographers use models and theories to explain these spatial patterns of land use, revealing how economic competition, transportation, and historical development shape where we live, work, and shop.
What You Should Be Able to Do
Explain how economic competition for land, as described by bid-rent theory, influences the internal structure of a city.
Compare and contrast the concentric-zone, sector, and multiple-nuclei models of urban structure.
Describe the features of the decentralized galactic city model.
Analyze how urban models for Latin America, Southeast Asia, and Africa reflect different historical and economic contexts than those of North America.
Key Developments & Analysis
The internal geography of cities is best understood through the lens of Spatial Patterns and Processes. The models we use are tools for identifying common patterns in land use and understanding the processes that create them.
Pattern: What is Where?
Urban models describe idealized spatial arrangements of different activities and social groups within a city.
Central Business District (CBD): Nearly all models begin with a core area of high-density commercial and office space, characterized by the tallest buildings and highest land values.
Concentric Rings: The earliest model (Burgess) depicts a city as a series of rings, with a zone of transition and industry surrounding the CBD, followed by rings of housing that improve in quality with distance from the center.
Wedge-like Sectors: A subsequent model (Hoyt) organizes the city into sectors or wedges that radiate out from the CBD, often following major transportation lines. A high-income housing sector, for example, might extend from the city center out along a scenic river or a commuter rail line.
Scattered Nuclei: As cities grow, they may develop multiple centers of activity, or nuclei, beyond the original CBD (Harris and Ullman). An airport, a university, or an industrial park can act as a new node, attracting related businesses and housing.
Decentralized Networks: The most contemporary model for North American cities (the galactic city) shows a landscape of suburban business parks, shopping malls, and residential areas all connected by a network of highways, with the original CBD being just one of many important centers.
International Variations: Models for cities outside North America show distinct patterns. Latin American cities often feature a commercial "spine" extending from the CBD, lined with elite housing. Southeast Asian cities may be centered on a port rather than a CBD. African cities can have multiple CBDs (colonial, traditional, and market) reflecting their complex history.
Process: How and Why Does This Happen?
The patterns described above are not accidental. They are the result of powerful social and economic processes.
Bid-Rent Theory: This is the fundamental economic process shaping urban land use. It explains how the price and demand for real estate change as the distance from the CBD increases. Different land users are willing to pay different amounts, or "bid," for locations. Commercial businesses, which rely on accessibility, will outbid all others for the central-most locations. As one moves away from the center, land becomes less expensive, and the dominant land use shifts from intensive commercial to residential and finally to industrial or agricultural uses.
Transportation and Accessibility: The shape of a city is profoundly influenced by its transportation technology. The concentric-zone model reflects a time of walking and limited public transit. The sector model emerged with the development of streetcar and rail lines, which allowed development to push outward along these corridors. The multiple-nuclei and galactic city models are products of the automobile and the construction of extensive highway systems, which made previously remote locations accessible and valuable.
Historical Context and Globalization: The structure of cities in Latin America, Africa, and Southeast Asia is heavily shaped by their colonial histories, rapid population growth, and roles in the global economy. Colonial powers often established port facilities and administrative centers that remain central to the city's layout. The presence of vast informal settlements on the periphery of many of these cities reflects patterns of rural-to-urban migration and economic inequality.
Impacts: Spatial Outcomes
Immediate Spatial Outcomes: The primary result of these processes is the clear segregation of land uses (e.g., commercial areas are separate from residential areas) and, often, the segregation of social groups by income or ethnicity.
Longer-Term Spatial Reorganization: Over time, these processes drive the evolution of the city's form. Many North American cities have transformed from a single-center structure (monocentric) to a multi-centered structure (polycentric) as transportation networks have improved and economic activities have decentralized to the suburbs.
Data & Organization Tools
This table provides a concise comparison of the major urban structure models.
| Model | Key Geographer(s) | Core Idea / Shape | Primary Driver(s) |
|---|---|---|---|
| Concentric-Zone | E.W. Burgess | A series of five rings of different land uses radiating from a central business district (CBD). | Bid-rent theory; social group succession. |
| Sector | Homer Hoyt | Land use is arranged in pie-shaped wedges or sectors radiating from the CBD along transportation lines. | Transportation corridors (e.g., rail lines, highways). |
| Multiple-Nuclei | C. Harris & E. Ullman | A city develops around several distinct centers of activity, or nuclei, rather than a single CBD. | Decentralization; specialized economic needs. |
| Galactic City | Chauncy Harris | A decentralized urban area with services and functions located in the suburbs and linked by a beltway. | Post-industrial economy; automobile dependence. |
| Latin American City | Griffin-Ford | A central CBD with a commercial "spine" surrounded by elite residential areas and zones of declining housing quality. | Colonial history; stark wealth inequality. |
| Southeast Asian City | T.G. McGee | A port zone acts as the city's center, with mixed land use zones and no formal CBD. | Colonial port history; rapid economic growth. |
| African City | de Blij | Features three CBDs (colonial, traditional, market), surrounded by ethnic neighborhoods and informal settlements. | Colonial legacy; ethnic diversity; rapid urbanization. |
Evidence Bank
Bid-rent theory: An economic geography theory that refers to how the price and demand for real estate change as the distance from the central business district (CBD) increases.
Burgess concentric-zone model: A model of the internal structure of cities in which social groups are spatially arranged in a series of rings.
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.
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.
Galactic city model: A model representing a city with a decentralized structure, where economic and residential functions have moved to the suburbs, creating independent nodes connected by a beltway.
Latin American city model: A model (also known as the Griffin-Ford model) showing a blend of traditional elements of Latin American culture with the forces of globalization that are reshaping the urban scene, featuring a prominent commercial spine and elite residential sector.
Southeast Asian city model: A model (also known as the McGee model) centered on a former colonial port zone, showing that the city serves as a gateway for international trade and includes zones of mixed land use.
African city model: A model showing the influence of colonialism, with three distinct CBDs (colonial, traditional, and market) and large, often peripheral, informal settlements.
Skill Snapshots
Pattern–Process
Pattern: High-density commercial skyscrapers are clustered in the city center. ↔ Process: Bid-rent theory dictates that commercial enterprises, which rely on maximum accessibility, can afford the highest land costs found at the city's core.
Pattern: An elite residential neighborhood extends outward from the center along a major boulevard. ↔ Process: Transportation corridors and historical development create a desirable "spine" for high-income residents, a key feature of the sector and Latin American city models.
Pattern: Large suburban business parks ("edge cities") are located near major highway interchanges. ↔ Process: Automobile-driven decentralization allows firms to access cheaper land and a suburban workforce, as described by the galactic city model.
Scale
Local vs. Regional: A local zoning ordinance may preserve a historic neighborhood's character, while a new regional beltway can fundamentally reshape the entire metropolitan area's structure by creating new nodes of economic activity.
North American vs. African City: The structure of a typical North American city is largely a product of post-industrial economic processes and automobile dependence, while the structure of many African cities is more directly shaped by a colonial legacy and rapid, often informal, urbanization.
CBD Function: In the classic Burgess model, the CBD is the single, dominant commercial hub. In the African city model, there may be three distinct CBDs (colonial, traditional, market) serving different economic and cultural functions within the same city.
Common Misconceptions & Clarifications
Models are not reality. Urban models are generalizations designed to simplify complex realities and identify broad patterns. No city perfectly fits any single model.
Models are not mutually exclusive. A real city often contains elements of multiple models simultaneously. It might have concentric rings of housing age, sectors of industry along a river, and multiple nuclei of commercial activity.
The classic models are time- and place-specific. The concentric, sector, and multiple-nuclei models were based on mid-20th century U.S. cities and do not perfectly explain contemporary or international urban forms.
"International" models are also generalizations. The models for Latin America, Southeast Asia, and Africa are useful for understanding common patterns but do not represent the unique structure of every city within those vast and diverse regions.
One-Paragraph Summary
The internal structure of cities follows predictable spatial patterns that can be explained by a set of key models and theories. At the core of urban economics is the bid-rent theory, which explains how competition for accessible land creates a logical arrangement of land uses. In North America, models have evolved from single-center concepts like the concentric-zone and sector models to multi-centered ones like the multiple-nuclei and galactic city models, reflecting the decentralizing impact of the automobile. To understand cities in other parts of the world, however, we must use region-specific models for Latin America, Southeast Asia, and Africa, which account for unique drivers like colonial history, rapid urbanization, and different economic trajectories. These models are essential tools for analyzing why cities are organized the way they are.