🚜AP Human Geography Review
30 Models and Theories to Know for AP Human Geography
30 Models and Theories to Know for AP Human Geography
40 Models and Theories to Know for AP Human Geography
This page highlights many of the major AP Human Geography models, theories, and spatial concepts students should recognize and apply on the current AP exam. Because AP Human Geography tests concepts as well as named models, students should also know core frameworks such as distance decay, arithmetic/physiological/agricultural density, carrying capacity, and major development and trade concepts from Unit 7. This is a models-and-theories roundup, not a complete list of the most-tested AP Human Geography concepts. Students should also prioritize major non-model concepts from the current course framework, including political boundary types and functions, devolution, centripetal and centrifugal forces, settlement patterns and land survey systems, agricultural production regions, urban infrastructure and density, and development measures such as HDI and GII.
This page also includes a few clearly labeled supplementary historical concepts. Priority APHG models include the Demographic Transition Model, Epidemiologic Transition Model, Malthus and Boserup, migration transition, diffusion, Von Thünen, central place theory, urban land-use models, rank-size rule and primate city, Rostow, dependency theory, world-systems theory, gravity model, and Weber.
For AP exam purposes, students should be able not only to define each model, but also to explain its assumptions, identify a real-world example, and discuss where the model works well or breaks down at local, national, or global scales.
Study Tips:
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- Create your own Quizlet deck and study these models and theories. Focus on what each model shows, its assumptions, limitations, and an example of how it applies. There are tons of decks already made (ex. here), but actually creating the deck is an important step in studying.
Quick note: On the AP exam, do not just memorize definitions. Be able to explain each model’s assumptions, where it works best, and its limitations. For example, Von Thünen assumes an isolated state with one market and equal transportation conditions, while urban models such as Burgess and Hoyt are simplified and do not perfectly fit all modern cities.
Unit 1 Models & Theories: Intro to Geography
1. Latitude, Longitude: Lat is fat! Long is Long! Latitude lines are horizontal, Longitude lines are vertical. Latitude measures distance north or south of the Equator (0°), and longitude measures distance east or west of the Prime Meridian (0°). Latitude lines are parallel circles, while longitude lines are meridians that converge at the poles.
2. GIS: Geographic Information Systems are used to analyze data on maps using layers!
3. Types of Thematic Maps (isoline, dot, proportional symbol, choropleth): Each type of map shows different information through the use of colors, lines, symbols, and distortion.
4. Distance Decay: Distance decay is the idea that the intensity of interaction between places usually decreases as distance increases. Geographers use it to explain why migration, trade, communication, and diffusion are often stronger between nearby places than distant ones, unless transportation or communication technology reduces that friction of distance.
APHG also applies geographic concepts at multiple scales: local, regional, national, and global.
Check out our unit 1 study guide!
⚡ Watch: AP Human Geography - Maps, Maps, Maps
Unit 2 Models & Theories: Population & Migration
5. Population Pyramids: Used to analyze the demographic makeup of a population including age and gender. They are especially useful for spotting patterns such as rapid growth, aging populations, or the effects of migration or conflict, but they must be interpreted in context rather than treated as a complete explanation by themselves.
6. Arithmetic Density: Arithmetic density is the total population divided by the total land area; it shows overall population concentration.
7. Physiological Density: Physiological density is the total population divided by the amount of arable land; it shows pressure people place on farmland.
8. Agricultural Density: Agricultural density is the number of farmers divided by the amount of arable land; it helps compare how labor-intensive or mechanized agriculture is.
9. Carrying Capacity: Carrying capacity is the maximum population an environment can sustainably support given available resources, technology, and patterns of consumption.
10. Demographic Transition Model: The Demographic Transition Model describes how birth rates, death rates, and natural increase tend to change as countries industrialize. The classic model has 4 stages, and some geographers add a possible stage 5 for countries with very low birth rates and aging populations. It is a generalized model, not a rule that all countries must follow exactly.
11. Epidemiologic Transition Model: The Epidemiologic Transition Model explains how the dominant causes of death tend to change as societies develop. Earlier stages are associated more with infectious and parasitic diseases linked to poor sanitation and limited health care, while later stages are associated more with chronic and degenerative diseases such as heart disease and cancer as life expectancy rises. Some geographers also note a later pattern of reemerging infectious diseases or diseases linked to lifestyle and aging. Like the DTM, this is a generalized model rather than a perfect rule.
⚡ Watch: AP Human Geography - Population Growth and Decline
12. Ravenstein’s Laws of Migration: Ravenstein’s Laws of Migration identify common migration patterns, such as most migrants moving short distances, migration often occurring in steps, and each migration flow creating a counterflow. Some of Ravenstein’s observations reflected 19th-century migration patterns, so they should be treated as tendencies rather than universal rules.
⚡ Watch: AP Human Geography - Migrations
13. Zelinsky Model of Migration Transition: The DTM does not reflect migration patterns, so Zelinsky developed this model to describe the types of migrations that occurs within a country depending on which demographic stage that country is in. For example, in a newly industrialized country in stage 2, the most common migration is rural to urban. However, a later stage country would experience more movement from urban to suburban.
14. Malthusian Theory of Population Growth: Thomas Malthus argued that population tends to grow geometrically (exponentially), while food production increases arithmetically (linearly). He believed this mismatch would create pressure on resources unless checked by factors such as famine, disease, war, or delayed family formation. AP Human Geography treats this as an influential theory with important limitations, especially because technological advances have increased food production.
15. Population Distribution and Migration Frameworks: Population distribution can be analyzed with the ecumene (permanently inhabited areas), arithmetic density, physiological density, and agricultural density. Students should also know push factors (such as conflict, persecution, and environmental hazards), pull factors (such as jobs, safety, and education), and intervening obstacles/opportunities when explaining migration decisions.
Check out our unit 2 study guide!
⚡ Watch: AP Human Geography - Malthusian Theory
Unit 3 Models & Theories: Culture
16. Diffusion Patterns and the S-Curve: AP Human Geography primarily expects students to identify and apply diffusion types—relocation, expansion, contagious, hierarchical, and stimulus diffusion. The S-curve is a helpful supplementary graph showing that adoption of an innovation often begins slowly, accelerates, and then levels off over time. Just think about trends like the bottle flip. It was a niche video with early adopters, then caught fire and spread everywhere, and then tapered off forever.
Types of Diffusion: AP Human Geography expects students to distinguish among relocation diffusion (spread through movement of people), expansion diffusion (spread outward from a source), contagious diffusion (rapid widespread expansion through direct contact), hierarchical diffusion (spread through a social or political hierarchy), and stimulus diffusion (spread of an underlying idea even when the original trait does not fully spread). The S-curve is useful for showing the rate of adoption, but students should especially know how to identify and apply the diffusion types in real examples.
Supplementary/historical models that may help contextualize APHG topics but are not core named models from the current course.
17. Language Tree: Languages have developed as offshoots of each other. The Indo-European family tree includes the most languages that have branched off, but there are other smaller trees too!
Students should also connect language and religion to diffusion processes. On the AP exam, be ready to explain how languages and religions spread through relocation diffusion, expansion diffusion, contagious diffusion, hierarchical diffusion, and syncretism or stimulus diffusion in specific historical and contemporary contexts.
⚡ Watch: AP Human Geography - Language and Culture
Check out our unit 3 study guide!
Unit 4 Models & Theories: Political Geography
These geopolitical theories are supplementary historical context. On the current AP Human Geography exam, students should prioritize applying political-geography concepts such as sovereignty, devolution, supranationalism, centripetal and centrifugal forces, boundary types, and the function of boundaries.
Supplementary/historical models that may help contextualize APHG topics but are not core named models from the current course.
18. Organic Theory: The organic theory, associated with Friedrich Ratzel, compares states to living organisms that grow and need resources to survive. The idea was later used to justify expansionist policies such as lebensraum, but students should understand it mainly as a historical geopolitical theory rather than a valid contemporary explanation of state behavior.
⚡ Watch: AP Human Geography - Supranationalism
19. Mackinder’s Heartland Theory: Halford Mackinder argued that control of the Eurasian "heartland"—roughly the interior of Eurasia, especially areas of Eastern Europe and central/northern Eurasia—would provide the strategic base for global power. In AP Human Geography, this should be treated as a historical geopolitical theory rather than a contemporary rule.
20. Spykman’s Rimland Theory: Spykman’s Rimland Theory argued that control of the coastal fringes of Eurasia—the rimland—was the key to global power. The rimland includes areas such as Western Europe, the Middle East, South Asia, East Asia, and Southeast Asia.
21. Domino Theory: From the Cold War, this theory stated that if one country "fell" to Communism, all of the surrounding countries would also fall like dominoes. Therefore, it was necessary for democratic countries to contain the spread of Communism so that others would not fall.
22. Core-Periphery Model: The core-periphery model describes an uneven spatial relationship in which core regions have greater economic development, infrastructure, and political power, while peripheral regions are less developed and often economically dependent. The model can be applied at global, national, and urban scales. It is helpful for comparing uneven development, but it can oversimplify places that do not fit neatly into fixed categories.
Check out our unit 4 study guide!
Unit 5 Models & Theories: Agriculture, Food, & Rural Land Use
23. Von Thunen Agricultural Location Theory: Von Thünen’s agricultural land-use model shows how different types of farming are arranged around a central market city based on transportation costs, land value, and perishability. Intensive and perishable products are located closer to the market, while more extensive land uses are farther away.
⚡ Watch: AP Human Geography - Types of Agriculture and Locations Around the World
24. Ester Boserup’s Theory: Ester Boserup argued that population growth can lead farmers to intensify agriculture and adopt new technologies, increasing food production. Her theory is often presented as a response to Malthus because it emphasizes human innovation rather than inevitable crisis.
25. Agricultural Production Regions: AP Human Geography expects students to identify and compare major farming types and regions, including shifting cultivation, pastoral nomadism, intensive subsistence agriculture, plantation agriculture, mixed crop and livestock, dairy, grain, Mediterranean, and commercial ranching. Students should connect these patterns to climate, labor, markets, transportation, and globalization.
26. Global System of Agriculture / Commodity Chains: AP Human Geography expects students to explain how agribusiness links producers, processors, distributors, and retailers across long commodity chains. Plantation agriculture is a key example: large-scale commercial farming in tropical regions, often producing export crops such as bananas, sugar, coffee, or rubber for distant markets. Students should be able to connect this system to colonial legacies, multinational corporations, labor conditions, transportation, and global trade.
⚡ Watch: AP Human Geography - Agricultural History and Revolutions
Check out our unit 5 study guide!
Unit 6 Models & Theories: Cities & Urban Land-Use Patterns and Processes
Current APHG also emphasizes density and land-use patterns, infrastructure, urban data, urban sustainability, and challenges of urban change. Students should be able to connect models like Burgess, Hoyt, multiple nuclei, bid-rent, rank-size, and primate city to issues such as transportation, segregation, suburbanization, sprawl, gentrification, underemployment, sanitation, and sustainability.
27. Christaller’s Central Place Theory: Christaller’s Central Place Theory explains the size, spacing, and distribution of settlements and services. It uses the concepts of threshold—the minimum number of people needed to support a good or service—and range—the maximum distance people are willing to travel to obtain that good or service. Based on simplifying assumptions, it produces a hexagonal or honeycomb pattern of market areas. It assumes an even surface, evenly distributed population, and equal transportation cost, so it is a simplified model rather than a literal description of all settlement patterns.
28. Burgess’ Concentric Zone Model: Burgess’ Concentric Zone Model describes a city growing outward in rings from the central business district (CBD). Just outside the CBD is the zone of transition, followed by working-class housing, then middle-class residential areas, and wealthier commuter suburbs farther from the center. The model is a simplification based on early industrial cities and does not fit all modern cities.
29. Gravity Model: The Gravity Model predicts that interaction between two places is greater when the places have larger populations and smaller when the distance between them is greater. Geographers use it to explain flows such as migration, commuting, trade, and communication. It is a useful general model, but real-world flows can also be shaped by borders, transportation networks, policy, and cultural ties.
30. Hoyt’s Sector Model: Hoyt’s Sector Model shows cities developing in wedges or sectors outward from the central business district, often along transportation routes. High-income residential sectors extend outward from the CBD, while lower-income and industrial sectors develop in other corridors.
31. Harris & Ullman’s Multiple Nuclei Model: Harris and Ullman’s Multiple Nuclei Model argues that cities develop around multiple nodes, or nuclei, such as ports, universities, business districts, and industrial parks. Different activities cluster in different parts of the city rather than around a single center.
Supplementary/historical models that may help contextualize APHG topics but are not core named models from the current course.
32. Borchert’s Evolution of the American Urban System: A generalized history of the urbanization of America through innovations in transportation. In the first stage of Sail/Wagon, cities developed near ports and major waterways. Then, by the mid-1800s, the railroads and steamboats led to cities developing on these routes. The early 20th century was characterized by long haul railroads and the growth of national railways. Much of the 20th century was then focused on the development of gasoline powered transportation including cars and planes. Since the 1970s, US cities have been developing based on service and information technology sectors (ex. Silicon Valley).
33. Zipf’s Rank-Size Rule: The rank-size rule is a pattern suggesting that in many countries the nth-largest city is about 1/n the size of the largest city. For example, the second-largest city may be about half the size of the largest, and the third-largest about one-third the size. It is a generalized pattern used to analyze urban systems, not a rule that every country follows exactly. This is a general pattern, not a law; some countries instead exhibit a primate city pattern.
34. Primate City Rule: A primate city is a country's largest city and is disproportionately larger and more influential than the next-largest cities. It often dominates the country's political, economic, and cultural life. Students should be able to compare the primate city pattern with the rank-size rule and explain what each pattern suggests about a country's urban system.
35. Bid-Rent Curve: The bid-rent curve shows that land prices and rent are highest near the central business district and decrease with distance from the city center because accessibility is most valuable in central locations.
⚡ Watch: AP Human Geography - Urban Models
Check out our unit 6 study guide!
Unit 7 Models & Theories: Industrial and Economic Development Patterns and Processes
Framework Note: AP Human Geography also expects students to use key development measures and frameworks, including GDP/GNI per capita, HDI, the Gender Inequality Index, sectoral employment, and sustainable development. Students should be able to compare what each measure reveals and what it leaves out.
36. Rostow’s Stages of Growth: This theory states that countries develop their industry in five stages over time. The highest stage is one of high mass consumption where there are tons of goods developed and consumed. Critics note that development does not always occur in one universal linear sequence.
37. Wallerstein’s World Systems Theory: The relationship between core and periphery countries is related to industrial development. Core countries sell high profit goods to consumers in semi- and periphery countries (less developed). Meanwhile semi- and periphery countries contribute cheap labor and raw materials to produce the goods. These theories help explain inequality but can oversimplify local variation and changing economic relationships.
38. Dependency Theory: Basically, the core countries depend on the periphery for labor and raw materials while the periphery depend on the core for goods. This dependency was created because of colonization. As periphery countries were colonized, their subsistence food production was replaced by cash crops and labor for the core countries to develop goods. Overtime, they became dependent on the core countries for food and consumer goods. These theories help explain inequality but can oversimplify local variation and changing economic relationships.
39. Comparative Advantage: Comparative advantage means a country or region can produce a good or service at a lower opportunity cost than another producer. This helps explain specialization and trade in the world economy. Like many economic models, it highlights efficiency but may leave out uneven labor conditions, environmental costs, or political barriers to trade.
40. Complementarity: Complementarity exists when one place has a supply of a good, service, or resource that another place demands, helping create trade or movement between them. In AP Human Geography, complementarity is often considered alongside transferability and intervening opportunity when explaining spatial interaction.
Trade Framework Note: Trade in APHG is also analyzed through concepts such as specialization, outsourcing/offshoring, export processing zones, and global supply chains.
41. Weber’s Least Cost Theory: Weber’s Least Cost Theory explains industrial location based on transportation, labor, and agglomeration costs. Bulk-reducing industries, which lose weight or volume during processing, tend to locate near raw materials. Bulk-gaining industries, whose finished products are heavier, bulkier, or more expensive to transport than their inputs after assembly or processing, tend to locate near markets. Firms may also choose locations with lower labor costs or benefits from agglomeration.
⚡ Watch: AP Human Geography - Industrial Location Theory
Check out our unit 7 study guide!
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