Larger and closer cities interact more — like gravitational attraction
Interaction between two places is proportional to the product of their populations divided by the distance squared. A big nearby city draws more migrants and trade than a larger distant one.
Three classic models of internal city organization
Burgess (concentric zones): CBD surrounded by rings. Hoyt (sectors): wedge-shaped zones along transport routes. Harris-Ullman (multiple nuclei): several business centers rather than one CBD.
Gentrification
Gentrification: reinvestment in low-income urban areas raises property values and displaces residents
Gentrification
Urban renewal process that benefits some while displacing others
Wealthier residents and businesses move into lower-income neighborhoods. Property values rise. Original lower-income residents are priced out (displaced). Revitalizes infrastructure but raises equity concerns.
Population Distribution
World population distribution: 90% live in Northern Hemisphere. Most in South/East Asia.
Population Distribution
Where people live — and why
Most densely populated: South Asia (India, Bangladesh), East Asia (China, Japan), Western Europe, Eastern US. Sparsely populated: deserts (Sahara, Australian Outback), rainforests (Amazon), polar regions, high mountains. Factors: climate, water availability, fertile soil, economic opportunity, historical settlement.
Urbanization Trends
Urbanization: cities grow as people move from rural to urban areas. Primate city = dominates country.
Urbanization Trends
The global shift from rural to urban living
More than 55% of world population now urban — projected to reach 68% by 2050. Primate city: disproportionately large city dominating a country's urban system (Bangkok, Paris, Mexico City). Urban primacy common in developing countries. Megacity: 10+ million population. Push from rural poverty + pull of urban opportunity.
Types of Regions
Ethnic vs cultural regions: formal (defined by one characteristic), functional (organized around a node), perceptual (mental image)
Types of Regions
Three ways geographers define regions
Formal (uniform) region: defined by one or more shared characteristics — the Corn Belt, the Bible Belt, Latin America. Functional (nodal) region: organized around a focal point or node — a city's commuter zone, a newspaper's circulation area. Perceptual (vernacular) region: exists in people's minds — 'the South,' 'the Middle East.'
Formal
Defined by shared characteristics
Functional
Organized around a central node
Perceptual
Exists in people's mental maps
Cultural Diffusion
Cultural diffusion: relocation (migrants carry culture), expansion (spreads outward), hierarchical (city to city first)
Cultural Diffusion
How cultural traits spread from place to place
Relocation diffusion: migrants physically carry culture to new locations. Expansion diffusion: spreads outward from source while staying there. Contagious: spreads through direct contact (disease model). Hierarchical: spreads from major cities to smaller ones, or elites to masses (fashion, music). Stimulus: idea sparks local innovation.
Malthusian Theory
Malthus: population grows geometrically, food supply arithmetically → inevitable famine
Malthusian Theory
Thomas Malthus's prediction about population and food supply
Malthus (1798): population doubles geometrically (1,2,4,8...) while food supply grows arithmetically (1,2,3,4...). Positive checks: famine, disease, war reduce population. Preventive checks: delayed marriage, celibacy. Neo-Malthusians: modern resource constraints. Critics: technology has expanded food supply — Green Revolution.
Suburbanization
Suburbanization: middle class leave cities for suburbs. White flight. Edge cities emerge.
Suburbanization
The post-WWII transformation of American urban geography
Post-WWII suburbanization: GI Bill mortgages, Interstate Highway System, cheap cars, white flight (racial segregation drove middle-class whites to suburbs). Consequences: urban decline, sprawl, car dependency. Edge cities (Garreau): suburban nodes with more jobs than bedrooms — Tysons Corner, Schaumburg. Now: 'new urbanism' pushes back.
Refugees and Forced Migration
Refugee vs immigrant: refugee = forced to flee persecution. Immigrant = voluntary movement.
Refugees and Forced Migration
The distinction between voluntary and involuntary migration
Refugee: person who has fled their country due to well-founded fear of persecution based on race, religion, nationality, political opinion, or social group (1951 UN Convention). Internally displaced person (IDP): forced from home but still in own country. Asylum seeker: requesting refugee status. Economic migrant: voluntary, seeking better opportunities.
Mnemonic
What it means
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🎓 Common Exam Questions
Q: Explain the DTM (Demographic Transition Model) — all four stages with examples.
A: DTM (Demographic Transition Model) describes how countries move from high birth and death rates to low birth and death rates as they develop. Stage 1 (Pre-industrial): high birth rates (children are economic assets, no contraception) and high death rates (disease, famine, war). Population low and stable. Stage 2 (Early industrial): death rates fall rapidly (medicine, sanitation, food supply) but birth rates remain high — population explosion. Sub-Saharan Africa and parts of South Asia. Stage 3 (Late industrial): birth rates begin to fall as women gain education and workforce access. Population still growing but slowing. Stage 4 (Post-industrial): low birth and death rates — population stable. Europe, Japan, US. Stage 5 (proposed): birth rates below death rates — natural decline. Germany, Italy, Japan.
Q: What is the gravity model of migration and what factors affect movement?
A: Gravity model: interaction between two places proportional to (Pop1 times Pop2) divided by Distance squared. Migration flows increase with population size of destination and decrease with distance. Factors that modify this: intervening opportunities (closer city with jobs reduces migration to distant city), intervening obstacles (borders, deserts, oceans, cost), step migration (rural to small city to large city in stages), chain migration (following family members already at destination). Lee's Push-Pull model: both origin and destination have positive and negative factors — migrants weigh these plus barriers. Most migration goes to nearest large city or places with existing diaspora communities.
Q: Explain the three main urban structure models and how they explain city layouts.
A: Three classic models: Burgess Concentric Zone Model (1925): Chicago-based. CBD at center, surrounded by rings — transition zone (factories, tenements), working-class housing, middle-class suburbs, commuter zone. Based on bid-rent theory (land value decreases with distance from CBD). Hoyt Sector Model (1939): wedge-shaped sectors radiating from CBD along transportation lines. High-income housing develops in desirable sectors (toward hills, away from industry). Multiple Nuclei Model (Harris and Ullman, 1945): cities have multiple nodes — not one CBD but several specialized centers (airport cluster, university area, industrial zone, suburban shopping). Reflects post-automobile city. All three based on US cities — don't account for government planning or post-modern fragmented cities.
Q: What is cultural diffusion and how has globalization changed it?
A: Cultural diffusion: spread of cultural elements (language, religion, music, food, technology) from one place to another. Types: Relocation diffusion — migrants physically carry culture (Spanish spread to Americas through colonization). Expansion diffusion — culture spreads from source outward. Contagious: through direct contact (folk music through a region). Hierarchical: from major centers first (hip-hop from NYC to global cities to rural areas). Stimulus diffusion: underlying idea spreads but adapted locally (McDonald's in India uses chicken not beef; serves vegetarian options). Globalization and the internet have dramatically accelerated diffusion — music, fashion, and food spread globally in days. Counter-current: cultural resistance and nationalism in response to perceived cultural homogenization.
Q: What is the difference between a refugee and an economic migrant?
A: Refugee (1951 UN Refugee Convention): person with well-founded fear of persecution based on race, religion, nationality, political opinion, or membership in a particular social group, who cannot return safely. Key rights: non-refoulement (cannot be returned to danger), right to apply for asylum, right to work and access services in host country. Economic migrant: moves voluntarily for better economic opportunities — no special legal protection, subject to ordinary immigration law. Grey areas: climate refugees (not covered by 1951 Convention), internally displaced persons (IDPs — displaced within own country). Current global count: over 100 million displaced people (UNHCR). Largest sources: Syria, Afghanistan, Ukraine, South Sudan, Venezuela.