African City Model Definition AP Human Geography: 2026 Study Guide

The African city model in AP Human Geography is a geographic framework describing the internal structure of cities in Sub-Saharan Africa, defined by a colonial-era central business district (CBD), a surrounding zone of informal trade, and distinct ethnic quarters. Developed by geographer Harm de Blij, it explains cities shaped by European colonialism and later rapid, often unplanned urbanization. Unlike models such as the concentric zone model, it accounts for informality, weak zoning, and multiple smaller business nodes rather than a single dominant core. Mastering this concept helps explain how colonial history still shapes urban land use across the continent.

Core Definition

The African city model, sometimes called the de Blij model, describes the typical spatial layout of a city in Sub-Saharan Africa. Its purpose is to generalize how these cities grew: a colonial power designed a European-style core for administration and trade, and after independence, rural migrants flooded in and built informal settlements around it. De Blij proposed it to fill a gap, since older models were based on North American and European cities.

It differs from other urban models in a few important ways. The concentric zone, sector, and multiple nuclei models assume formal housing, functional zoning, and a single dominant CBD. In the African city model, the colonial CBD may be less economically powerful than expected, and a separate informal business center often rivals it. Land use is also more mixed, because many residents work in the informal economy rather than commuting to a formal job downtown. Cities grow outward in irregular rings rather than neat concentric circles, often following major roads or ethnic settlement patterns.

A related model, the Southeast Asian city model, also features a colonial port core, but its zones are more clearly separated. The African version is typically the more fragmented of the two.

Key Structural Features

The model arranges a Sub-Saharan African city into a set of recognizable zones. Exact names vary by textbook, but the pattern is consistent enough to appear on the AP exam.

Zones of the model

• Colonial CBD — the former administrative and commercial core. It has the widest paved roads, government buildings, and formal shops, and reflects European planning.
• Informal economy zone — a market area just outside the colonial CBD where street vendors and informal traders concentrate. This often functions as a second, more active business center.
• Ethnic neighborhoods — residential quarters historically divided by ethnic group or tribe, often near the informal business zone.
• Peripheral areas — rapidly expanding informal settlements (sometimes called squatter settlements) on the outskirts, where most residents live.

A short worked example makes this concrete. In a city like Nairobi, the formal downtown with banks and government offices resembles the colonial CBD, while areas such as Kibera illustrate peripheral informal settlements where housing is self-built and services are limited. The large open-air markets and street trading between them fit the informal economy zone. The pattern shows up in many cities, though the exact layout varies.

Several patterns run through these zones. The model is not concentric but fragmented, with business activity in more than one place. Residential density is highest in the periphery, not the center, which reverses the pattern in most Western models. Ethnic clustering is a defining feature, and colonial infrastructure like rail lines and ports continues to anchor growth along specific corridors.

AP Exam Application

On the AP Human Geography exam, this model usually appears in the Cities and Urban Land-Use unit as a multiple-choice question or in a free-response question about urban models. You may be asked to identify its originator, describe its zones, or compare it with another model. College Board’s course materials treat urban models as tools for explaining patterns of land use, so expect questions that ask why a zone exists, not just what it is.

The most common task is a comparison. For instance, you might be asked how the African city model differs from the concentric zone model. A strong answer notes the informal economy, the multiple business nodes, and the peripheral high-density settlements. A second common task is application: given a scenario about a specific African city, use the model to explain its growth pattern.

A few practical strategies help. First, memorize the zones and be ready to define “colonial CBD” and “informal economy zone” on demand. Second, connect the model to broader concepts like colonialism, urbanization, and the informal sector. Third, practice writing one clear comparison paragraph, since comparing urban models is a recurring skill. The National Geographic Society offers resources on urbanization and population patterns that can reinforce this context.

Strengths and Criticisms

The model’s main strength is that it gives a workable, recognizable framework for cities that older models ignore. It captures the colonial legacy, the informal economy, and ethnic clustering, all of which are central to how Sub-Saharan African cities actually function. For an exam, its simple structure is easy to recall and apply.

The main criticism is overgeneralization. Africa is enormous and diverse, spanning North Africa, the Sahel, the coast, and the interior, with very different colonial histories and economies. Some cities have a dominant formal CBD, while others have almost none. The model also reflects a point in time and may fit older post-colonial cities better than fast-changing ones today. Critics note that treating such a varied continent as one pattern can flatten real differences. North African cities such as Cairo carry Mediterranean and Islamic urban traditions the Sub-Saharan framework does not address well, and southern African cities bear the imprint of apartheid-era planning.

A balanced answer acknowledges both sides. The model is a useful generalization, not a strict map. It identifies tendencies rather than rules, and its value on the exam is as a comparative tool.

Key Takeaways

• The African city model, by Harm de Blij, describes Sub-Saharan African cities with a colonial CBD, an informal economy zone, ethnic neighborhoods, and sprawling peripheral settlements.
• It differs from traditional models by emphasizing informal activity, multiple business nodes, and high-density peripheral housing.
• On the AP exam, expect it in the Cities and Urban Land-Use unit, often in comparison or application questions.
• Its strength is capturing colonial legacies and informality; its main weakness is generalizing across a highly diverse continent.