Human geography tricks that make population click

Push factors = leave. Pull factors = arrive.

Migration Theory — Push: poverty, war, drought, persecution, lack of jobs. Pull: employment, safety, family, better healthcare. Ravenstein's Laws: most migrants move short distances, step-by-step.

DTM (Demographic Transition Model): 4 stages from high birth and death rates to low birth and death rates → population boom in the middle

Stage 1High birth, high death — pre-industrial

Stage 2Death rate falls — rapid growth

Stage 3Birth rate falls — slowing growth

Stage 4Both low — stable population

Gravity model: interaction ∝ (Pop₁ × Pop₂) / Distance²

Gravity Model — 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.

Urban models: concentric rings (Burgess), sector (Hoyt), multiple nuclei (Harris-Ullman)

Urban Structure Models — 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: reinvestment in low-income urban areas raises property values and displaces residents

Gentrification — 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.

World population distribution: 90% live in Northern Hemisphere. Most in South/East Asia.

Population Distribution — 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: cities grow as people move from rural to urban areas. Primate city = dominates country.

Urbanization Trends — 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.

Ethnic vs cultural regions: formal (defined by one characteristic), functional (organized around a node), perceptual (mental image)

FormalDefined by shared characteristics

FunctionalOrganized around a central node

PerceptualExists in people's mental maps

Cultural diffusion: relocation (migrants carry culture), expansion (spreads outward), hierarchical (city to city first)

Cultural Diffusion — 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.

Malthus: population grows geometrically, food supply arithmetically → inevitable famine

Malthusian Theory — 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: middle class leave cities for suburbs. White flight. Edge cities emerge.

Suburbanization — 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.

Refugee vs immigrant: refugee = forced to flee persecution. Immigrant = voluntary movement.

Refugees and Forced 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.