All 18 Named Models
Application Guide

As countries industrialize, CDR falls first (medicine/sanitation), then CBR falls later (changing norms). The lag between falling CDR and falling CBR = population explosion in Stage 2–3.

Given a population pyramid or CBR/CDR data, identify the stage. Explain WHY a country is transitioning between stages. Predict future population trajectory.

Based on Western European experience — doesn't fully fit countries that industrialized later or differently. Stage 5 was added after the original model. Doesn't account for AIDS-era CDR spikes.

Epidemiological Transition Model — same stages but focuses specifically on causes of death shifting from infectious to chronic/degenerative diseases.

As countries develop, causes of death shift: Stage 1–2 = pestilence/famine; Stage 3 = receding pandemics; Stage 4 = degenerative/lifestyle diseases (heart disease, cancer); Stage 5 = re-emerging infectious diseases.

Given a description of dominant disease burden (infectious vs. chronic), identify the stage. Explain why aging populations in Stage 4 face higher healthcare costs.

Stage 5 (re-emerging diseases) was controversial until COVID-19 made it prescient. Doesn't capture simultaneous disease burden in countries managing both infectious AND chronic diseases.

DTM — they parallel each other but ETM focuses on causes of death specifically, not just the CDR/CBR relationship.

Population grows geometrically (1→2→4→8) but food grows arithmetically (1→2→3→4). Eventually population outstrips food supply → positive checks (famine, disease, war) or preventive checks (delayed marriage, celibacy).

Explain why Malthus has been criticized (Green Revolution proved food supply can grow faster than population). Identify neo-Malthusian concern: modern resource limits (water, energy) instead of food.

Dramatically underestimated technological innovation. Food production growth outpaced population growth in the 20th century. Neo-Malthusians update it to include environmental limits beyond food.

DTM — Malthus predicts crisis and collapse; DTM describes a managed transition. They make opposite predictions about population trajectories.

Key laws: (1) Most migrants move short distances. (2) Migration occurs in steps (step migration). (3) Long-distance migrants go to major cities. (4) Rural dwellers are more migratory than urban. (5) Each migration flow produces a counter-flow. (6) Women more migratory than men over short distances.

Given a migration scenario, identify which Ravenstein law applies. Explain why distance matters in migration decisions (friction of distance, distance decay).

Based on 19th-century UK/US census data. Modern air travel and the internet have weakened the distance-based laws. Does not capture forced migration or refugee flows, which violate the "voluntary" assumption.

Lee's Push-Pull Model — Ravenstein describes patterns; Lee explains motivations. Use Ravenstein for "what patterns of migration exist?"; use Lee for "why do people migrate?"

Migration decisions result from: Push factors (negative conditions at origin: unemployment, conflict, poverty, environmental hazard); Pull factors (positive conditions at destination: jobs, safety, education); Intervening obstacles (cost, distance, borders, discrimination); Personal factors (age, family, risk tolerance).

Given a migration scenario, identify specific push and pull factors AND at least one intervening obstacle. FRQ high-frequency: "explain how push and pull factors AND intervening obstacles shaped [specific migration]."

Treats migration as a rational individual cost-benefit analysis — underestimates role of social networks, cultural traditions, and structural forces (colonialism, labor recruitment). Doesn't explain why some people in identical conditions migrate and others don't.

Gravity Model — gravity predicts volume of migration between two places; Lee explains why individuals decide to migrate.

Interaction between two places is proportional to the product of their populations and inversely proportional to the square of distance. Larger cities attract more migrants from further away. Explains why NYC attracts global migration while small towns attract only local movement.

Compare two cities' migration-attracting power. Explain why doubling distance reduces interaction by 75% (squared relationship). Explain space-time compression effects on gravity model in the internet age.

Distance is decreasingly relevant with modern transportation. Cultural, linguistic, and historical ties between origin and destination (colonial links) explain flows better than distance alone in some corridors.

Christaller's Central Place Theory — both involve city size and distance, but Gravity describes interaction volume; Central Place describes service area hierarchy.

5 concentric rings from CBD outward: (1) CBD, (2) Zone of Transition (factories, deteriorating housing), (3) Working-class residential, (4) Middle-class residential, (5) Commuter zone. Poorest live closest to CBD.

Identify from cross-section diagram. Explain why poor live in Zone 2 (proximity to factory jobs). Describe ONE limitation (assumes uniform terrain, single transport mode, pre-automobile).

Based on early 20th-century industrial Chicago. Doesn't fit post-automobile suburbanization, gentrification (wealthy return to inner city), edge cities, or cities in the Global South.

Latin American City Model (Griffin-Ford) — in Latin America, wealthy live near CBD (opposite of Burgess); poor on periphery.

City growth occurs in wedge-shaped sectors radiating from CBD along transportation corridors (railroads, highways). High-income residential sectors grow outward in the same wedge, away from industrial sectors. Sectors reflect transportation influence.

Identify from diagram by looking for pie-slice shapes rather than rings. Explain why high-income uses avoid industrial sectors. Explain how railroad/highway construction shaped sector development.

Assumes linear transportation corridors dominate land use. Doesn't account for multiple CBDs, edge cities, or Global South city patterns. Relatively rare in AP stimulus questions.

Burgess — key distinguishing feature: Hoyt = wedge sectors, Burgess = concentric rings. If the diagram shows pie slices, it's Hoyt.

Cities develop around multiple nodes (nuclei) rather than one CBD. Different activities cluster based on: (1) similar activities agglomerate; (2) dissimilar activities repel each other; (3) some activities require specific locations; (4) some activities can't afford high-rent areas.

Identify from diagram by looking for irregular patches, not rings or wedges. Explain agglomeration economies. Most applicable to modern polycentric American cities with edge cities.

Most complex of the three North American models — harder to predict specific land use locations. Less prescriptive than Burgess or Hoyt about where activities will be.

The three models together: Burgess = rings, Hoyt = wedges, Harris-Ullman = irregular multiple nodes. Shape of the diagram tells you which model.

Commercial spine (mall) extends from CBD; wealthy residential in/near CBD and along the spine; squatter settlements (favelas, colonias) on periphery; middle-class residential in middle rings. Opposite pattern from Burgess — wealthy near center, poor on edge.

Compare with Burgess model (opposite income gradient). Explain why peripheral squatter settlements form (rapid rural-urban migration exceeds formal housing supply). Examples: São Paulo, Mexico City, Buenos Aires.

Gentrification and formal urban development in Latin America are making peripheries more complex. The model was developed for 1970s–80s cities — newer Latin American cities may not fit as cleanly.

Burgess model — the key distinction is the income gradient direction. When the question says "Latin American city," immediately recall that wealthy = CBD and spine; poor = periphery.

Different land users (retail, office, residential, industrial) compete for land. Each user bids a price that declines with distance from CBD. Retail bids highest near CBD (maximum customer access); residential outbids retail in mid-ring; industrial occupies outermost land.

Interpret a bid-rent curve diagram. Explain why retail pays highest rents near CBD. Explain why apartment buildings cluster near CBD (compensate high land cost with vertical density). Explain land use transitions.

Assumes all locations on a ring are equally accessible — ignores transport corridors (Hoyt's insight). Doesn't account for zoning laws or historical industrial inertia.

Von Thünen (agricultural bid-rent) — both involve decreasing land value with distance from a center, but Von Thünen applies to agricultural land around a market city; Alonso's bid-rent applies within an urban area.

Rank-Size Rule: the nth-largest city = 1/n × largest city's population (2nd city = 1/2 largest; 3rd = 1/3, etc.). Primate City: when the largest city is disproportionately large (≥2× second city) — suggests over-concentration and uneven development.

Given a table of city populations, determine if rank-size rule holds or if there is a primate city. Explain what a primate city suggests about development (often: colonial history, extreme centralization, rural-urban migration concentration).

Many developed countries (USA, Germany) actually fit rank-size well; primate cities are more common in former colonies. The rule is a description, not an explanation of why cities grow to certain sizes.

Christaller's Central Place Theory — both are about city hierarchy, but rank-size is empirical (describes actual populations); Christaller is theoretical (predicts service area geometry).

Settlements form a hierarchy based on the services they offer. Range: maximum distance consumers travel for a service. Threshold: minimum population needed to sustain a service. Higher-order services (hospitals, universities) require larger threshold → fewer, farther apart. Hexagonal trade areas minimize overlap.

Explain why hardware stores are more common than hospitals (lower threshold, smaller range). Explain how the internet is altering range and threshold for many services (online retail eliminates geographic range).

Assumes flat, uniform surface with evenly distributed population — never found in reality. E-commerce eliminates the geographic range concept for many goods. Historical and political factors shape settlement patterns as much as service economics.

Rank-Size Rule — Christaller predicts hierarchical relationships theoretically; Rank-Size observes them empirically. Christaller explains why a hierarchy exists; rank-size describes what that hierarchy looks like.

Agricultural land use arranges in concentric zones around a market city based on transportation cost relative to product value. Zone 1: Market gardening/dairy (perishable, high transport cost per km). Zone 2: Forest/timber (heavy, cheap → must be close). Zone 3: Grain (durable, light). Zone 4: Ranching (animals walk to market).

Identify zones from a diagram. Explain why forestry is Zone 2 not Zone 4 (transportation cost logic, not space need). Explain how refrigeration and transport technology altered the model. Most FRQ-tested model in Unit 5.

Assumes flat plain, single market city, uniform soil, no transport variation. Modern refrigeration and containerized shipping dramatically altered perishability constraints. Global commodity chains mean dairy may come from 2,000 km away.

Bid-Rent Theory (Alonso) — Von Thünen = agricultural land use around a market; Bid-Rent = urban land use within a city. Both involve zones and declining value with distance, but applied to different contexts.

All countries follow the same 5-stage linear path: (1) Traditional society, (2) Preconditions for takeoff, (3) Takeoff (industrial growth, rising savings rate), (4) Drive to maturity, (5) High mass consumption. Implies all countries can/will reach Stage 5 through the same path.

Identify which stage a described country is in from data clues. Compare with World-Systems Theory (same question, totally different explanation). Identify one limitation (Eurocentric, ignores colonial exploitation).

Based on Western European/American experience. Assumes the same path is available to all — ignores that colonial extraction may have prevented developing countries from accumulating the capital needed for Stage 3. Criticized as ideological (written during Cold War to show capitalism's path to prosperity).

World-Systems Theory — Rostow says all countries can develop through the same path; WST says the global system is structured to prevent peripheral countries from reaching core status.

The global capitalist economy is permanently stratified into: Core (high-wage, high-tech, capital-intensive production; wealthy nations); Semi-periphery (transitional; both exploiting and exploited); Periphery (low-wage, raw material export, structurally disadvantaged). Core nations exploit periphery → inequality is structural, not developmental lag.

Classify a country as core/semi-periphery/periphery and justify. Explain how the New International Division of Labor (NIDL) reflects world-systems dynamics. Compare with Rostow on what causes global inequality.

Some countries (South Korea, Taiwan, China) have moved from periphery toward semi-periphery/core, suggesting the hierarchy isn't fixed. May over-determine outcomes and understate the role of domestic institutions in development.

Dependency Theory — very similar, but Dependency Theory (Cardoso, Frank) focuses specifically on Latin America; World-Systems is a global framework. On the AP exam, treat them as closely related: both argue structural global inequality prevents peripheral development.

Industries locate where total costs (transportation + labor + agglomeration) are minimized. Weight-losing industries (ore → metal) locate near raw materials. Weight-gaining industries (bottling, baking) locate near markets. Footloose industries (software) locate based on labor/agglomeration.

Given an industry description, determine if it is weight-losing, weight-gaining, or footloose and predict its location. Explain why steel mills locate near coal/iron ore. Explain why call centers locate in low-wage regions (footloose).

Space-time compression and information economy have made many industries footloose — transportation cost is decreasingly deterministic. Government incentives (subsidies, tax breaks) frequently override pure cost minimization.

Von Thünen — both involve distance-cost tradeoffs and location theory, but Weber applies to industrial location; Von Thünen applies to agricultural land use. Different contexts, similar logic.