Population & Migration Patterns: every key term you need (+ practice quiz)
65 flashcard terms for AP Human Geography Unit 2, written to match the course framework. Study them here, then drill them as interactive flashcards, or test yourself with the 20-question quiz — free, no account needed.
The pattern of where people live across Earth's surface — highly uneven, with roughly 90% of people living north of the equator and clustered in a few dense regions.
Population Density
A measure of how crowded a place is — arithmetic, physiological, or agricultural density each highlight a different aspect of crowding and land pressure.
Ecumene
The portion of Earth's surface permanently inhabited by humans; excludes deserts, polar regions, and other areas too harsh for permanent settlement.
Population Pyramid
A graph showing a population's age-sex structure as horizontal bars — its shape reveals growth rate, dependency, and stage of demographic transition.
Expansive Population Pyramid
A wide-based, triangular pyramid showing many young people and high birth rates — typical of countries in early demographic transition stages (rapid growth).
Constrictive Population Pyramid
A pyramid narrower at the base than the middle, showing declining birth rates and an aging population — typical of countries transitioning toward slower growth.
Stationary Population Pyramid
A pyramid with roughly equal-width bars across age groups, showing low birth and death rates — typical of highly developed countries with stable population size.
Dependency Ratio
The ratio of dependents (under 15 and over 64) to the working-age population (15–64); a high ratio strains the economy supporting non-workers.
Crude Birth Rate (CBR)
The number of live births per 1,000 people in a population per year — a basic (or 'crude') measure not adjusted for age or sex structure.
Crude Death Rate (CDR)
The number of deaths per 1,000 people in a population per year — like CBR, unadjusted for the population's age structure.
Rate of Natural Increase (RNI)
The percentage growth rate of a population from births and deaths alone (CBR − CDR, divided by 10), excluding migration.
Total Fertility Rate (TFR)
The average number of children a woman would have during her childbearing years at current birth rates — a key predictor of future population growth.
Replacement-Level Fertility
A TFR of about 2.1 children per woman, the rate needed to keep a population stable (accounting for child mortality) without migration.
Infant Mortality Rate (IMR)
The number of deaths of infants under age one per 1,000 live births — a sensitive indicator of a country's healthcare access and development level.
Life Expectancy
The average number of years a person is expected to live at birth, given current mortality patterns — generally higher in more developed countries.
Doubling Time
The number of years it takes a population to double in size at its current rate of natural increase; higher RNI means shorter doubling time.
Demographic Transition Model (DTM)
A model describing how a country's birth and death rates (and total population) change as it industrializes, moving through predictable stages.
DTM Stage 1 — Low Growth
High birth and death rates roughly balance, keeping population size low and stable; describes pre-industrial societies (no country remains here today).
DTM Stage 2 — High Growth
Death rates fall sharply (better food, sanitation, medicine) while birth rates stay high, causing rapid population growth — the steepest part of the 'population explosion.'
DTM Stage 3 — Moderating Growth
Birth rates begin falling (urbanization, women's education, contraception, industrialization) while death rates stay low, so growth slows but continues.
DTM Stage 4 — Low Growth
Birth and death rates are both low, and population size stabilizes; characteristic of most developed countries today.
DTM Stage 5 — Decline
Birth rates fall below death rates, causing natural population decrease; some scholars add this stage for countries like Japan and parts of Europe.
Epidemiological Transition Model
A companion model tracking the shift in leading causes of death — from infectious/parasitic diseases (Stage 2 countries) to chronic/degenerative diseases (Stage 4 countries).
Malthusian Theory
Thomas Malthus's 1798 prediction that population grows exponentially while food supply grows only arithmetically, leading to inevitable famine and crisis unless growth is checked.
Neo-Malthusians
Modern thinkers who revive Malthus's concerns, focusing on resource depletion, environmental degradation, and overpopulation's strain on sustainability.
Critiques of Malthus
Critics note Malthus underestimated technological gains in food production (Green Revolution) and that many high-population regions have avoided mass famine through trade and innovation.
Boserup's Theory
Ester Boserup's counter-argument: population growth itself drives agricultural innovation, as necessity pushes societies to intensify food production — the opposite causal direction from Malthus.
Overpopulation
A situation where a region's population exceeds the carrying capacity of its resources and environment to sustainably support it.
Carrying Capacity
The maximum population size an environment can sustainably support given its available resources and technology.
Population Composition
The structure of a population by age, sex, or other characteristics — the basis for constructing and interpreting population pyramids.
Sex Ratio
The ratio of males to females in a population, which can be skewed by cultural son preference, war, labor migration, or gender-selective policies.
Migration
The permanent or semi-permanent movement of people from one place to another, changing their place of residence.
Emigration vs. Immigration
Emigration is movement OUT of a place (from the origin's perspective); immigration is movement INTO a place (from the destination's perspective).
Net Migration
The difference between immigration and emigration for a place; positive net migration means more people arrive than leave.
Push Factors
Conditions that drive people to leave a place — war, persecution, poverty, natural disaster, lack of opportunity, environmental degradation.
Pull Factors
Conditions that attract migrants to a destination — job opportunities, safety, family ties, better climate, political or religious freedom.
Ravenstein's Laws of Migration
19th-century generalizations: most migrants move short distances, migration occurs in stages, long-distance migrants prefer urban destinations, and each migration flow produces a counterflow.
Distance Decay in Migration
Migration is more common over short distances than long ones, since the friction of distance (cost, time, unfamiliarity) discourages far moves.
Intervening Obstacles
Barriers — physical (mountains, oceans), political (borders, visa laws), or economic (cost of travel) — that hinder migration between an origin and destination.
Intervening Opportunity
An attractive closer destination that satisfies a migrant's needs, reducing the likelihood they will continue on to a farther, originally intended destination.
Step Migration
Migration completed in stages, often moving first to a nearby town, then a regional city, then eventually a larger metropolis or another country.
Chain Migration
A pattern in which migrants follow relatives or community members who already settled in a destination, creating clustered ethnic communities.
Voluntary Migration
Migration by choice, typically driven by economic or lifestyle pull factors (e.g., moving for a better job).
Forced Migration
Migration due to circumstances beyond a person's control — conflict, persecution, disaster, or trafficking — where the migrant has little or no choice.
Refugee
A person forced to flee their country due to a well-founded fear of persecution, war, or violence, and who has crossed an international border.
Internally Displaced Person (IDP)
A person forced to flee their home for reasons similar to refugees but who has NOT crossed an international border — remains within their own country.
Asylum Seeker
A person who has crossed a border seeking refugee status but whose claim has not yet been legally decided.
Transnational Migration
Migration in which people maintain strong social, economic, and cultural ties across two or more countries simultaneously, rather than fully assimilating into one.
Circular (Seasonal) Migration
Repeated, temporary movement between an origin and destination (e.g., agricultural guest workers) without permanent relocation.
Internal Migration
Movement within a single country's borders — does not cross international boundaries (e.g., rural-to-urban migration).
International Migration
Movement across a national border, from one country to another.
Rural-to-Urban Migration
The movement of people from rural areas to cities, driven by push factors (lack of farmland, mechanization) and pull factors (jobs, services) — a major force reshaping developing countries.
Urbanization
The growing proportion of a country's population living in cities, closely tied to rural-to-urban migration and economic development.
Counterurbanization
Movement of people FROM urban areas TO smaller towns or rural areas, often seen in highly developed countries seeking lower costs or quality of life.
Interregional Migration
Movement between different regions of the same country (e.g., the U.S. Sun Belt migration from the Rust Belt).
Intraregional Migration
Movement within the same region, such as suburbanization — people moving from central cities to surrounding suburbs.
Guest Worker Programs
Government arrangements allowing foreign workers to migrate temporarily for labor, often in agriculture or manufacturing, without a path to permanent residency.
Brain Drain
The emigration of a country's highly educated or skilled workers, often to more developed countries — a loss of human capital for the origin country.
Remittances
Money migrants send back to family or communities in their origin country — a major source of income for many developing economies.
Environmental (Climate) Migrants
People forced to move due to environmental change — drought, desertification, sea-level rise, or natural disasters — a growing and legally complicated migration category.
Gravity Model of Migration
Predicts migration flow between two places is proportional to the product of their populations and inversely proportional to the distance between them.
Zelinsky's Migration Transition Model
Links migration patterns to a society's stage in the demographic transition — international emigration peaks in Stage 2, later shifting to internal/interregional movement in Stages 3–4.
Immigration Policy Examples
Quota systems, points-based systems (favoring skilled workers), and family reunification programs are common ways destination countries regulate immigration.
Xenophobia
Fear or hostility toward immigrants or people perceived as foreign — often a political reaction to large or rapid migration flows.
Population Momentum
Continued population growth even after fertility rates decline to replacement level, because a large young cohort still moves into reproductive age.