AP Human Geography Unit 6 Notes: Understanding Urban Form, Function, and Change

City size (in geography)

Usually refers to a city’s population (often the metropolitan population rather than just the city limits).

Distribution of cities

How city sizes relate to one another within a country or region; patterns can reflect development, history, transportation, and centralization of power.

Rank-size rule

Model of an “idealized” urban hierarchy where the 2nd-largest city is about 1/2 the largest, the 3rd about 1/3, etc.; used as a baseline for comparison, not a law.

Rank-size equation (Pn = P1/n)

Formula stating that the population of the city ranked n (Pn) equals the largest city’s population (P1) divided by its rank (n).

Primate city

A country’s leading city that is disproportionately large and dominates the economy, politics, and culture beyond what rank-size would predict (often also the capital/gateway city).

Agglomeration effects

Self-reinforcing advantages that occur when jobs and services cluster in one place, making that location even more attractive for firms and migrants.

Central Business District (CBD)

Typically the most accessible part of the urban area, with high land values and intensive land use (often high-rise offices, corporate services, government, and transit hubs).

Concentric Zone Model (Burgess)

Urban land-use model where a city grows outward in rings from the CBD, historically including a nearby “zone in transition” and more distant commuter suburbs.

Zone in transition

Area near the CBD in the Concentric Zone Model characterized by mixed land uses and aging housing; historically associated with poverty and recent immigrants as wealthier residents moved outward.

Invasion and succession

Process where new groups or land uses move into a neighborhood (invasion) and over time replace existing ones (succession), reshaping urban patterns.

Filtering

Housing process where older housing becomes more affordable over time as it ages and (often) declines in relative desirability, influencing who can live where.

Sector Model (Hoyt)

Urban land-use model where the city develops in wedge-shaped sectors radiating from the CBD, often along transportation routes.

Multiple Nuclei Model (Harris and Ullman)

Model proposing that cities develop multiple centers (nuclei) for different activities (e.g., downtown, university district, airport/industrial area, shopping/office nodes).

Peripheral (Galactic) Model

Model describing an outer ring (often a beltway) with multiple business districts on the periphery, supported by high automobile accessibility.

Edge city

Major suburban node of offices, retail, and entertainment that functions like a secondary CBD, often located near highways/beltways.

Latin American City Model (Griffin-Ford)

Model emphasizing a strong CBD connected to an elite residential corridor (spine), with inequality often visible in peripheral zones that may include informal housing.

Spine (Latin American model)

A corridor of development—often along a major boulevard—linking the CBD to high-income residential areas and amenities.

Squatter settlement

Informal housing area, often on the urban periphery, where residents may lack adequate infrastructure due to rapid growth and limited formal housing supply.

Bid-rent theory

Explains how different land users bid different amounts for locations based on accessibility; high-traffic commercial users often outbid others for central sites, pushing many residences outward.

Floor-area ratio (FAR)

Planning measure comparing a building’s total floor area to the size of its lot; higher FAR generally indicates more intensive (often more vertical) development.

Residential density

Density measure focusing on people or housing units per residential land area (useful because parks/industrial land can distort overall density).

Zoning

Legal tool designating what can be built where (e.g., residential/commercial/industrial) and regulating features like height, lot size, parking, and allowed density.

Urban sprawl

Outward expansion of urban development characterized by low density, car dependence, and often single-use zoning patterns, leading to high land consumption.

Smart growth

Planning approach aimed at limiting sprawl and improving efficiency/livability through strategies such as mixed-use development, transit-oriented development, infill, and growth boundaries/greenbelts.

Gentrification

Process where higher-income residents and investment move into a historically lower-income neighborhood, raising property values and often changing land use/culture, with potential displacement of long-time residents.