Population & Migration Patterns: every key term you need (+ practice quiz)
101 flashcard terms for AP Human Geography Unit 2, written to match the course framework. Read them here, drill them as flashcards, or take the 47-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).
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.
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.
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.
Ecumene
The portion of Earth's surface permanently inhabited by humans; expanded over time but still concentrated in mid-latitude, low-lying, and coastal areas.
Carrying Capacity
The maximum population an area can support given its resources and technology; can rise with technological change.
Total Fertility Rate (TFR)
The average number of children a woman is expected to have during her childbearing years; replacement level is about 2.1.
Infant Mortality Rate (IMR)
The number of deaths of children under one year per 1,000 live births; a sensitive indicator of health-care quality and development.
Rate of Natural Increase (RNI)
Crude birth rate minus crude death rate, expressed as a percentage; excludes migration.
Doubling Time
The years needed for a population to double at its current RNI, approximated by the Rule of 70 (70 ÷ RNI %).
Dependency Ratio
The number of people under 15 and over 64 compared with the working-age population; high ratios strain workers and government budgets.
A bar graph of age and sex structure; a wide base signals rapid growth, a rectangular shape signals stability, and a top-heavy shape signals decline.
Epidemiological Transition Model
Omran's model linking DTM stages to causes of death: pestilence and famine, receding pandemics, degenerative diseases, delayed degenerative diseases, and possibly re-emerging infectious diseases.
Malthusian Theory
Malthus (1798) argued population grows geometrically while food grows arithmetically, leading to crisis; critics note technology and falling fertility have delayed this.
Neo-Malthusians
Modern thinkers who apply Malthus's logic to resources beyond food, such as water and energy, warning of overshoot.
Boserup Thesis
Ester Boserup's counter to Malthus: population pressure stimulates agricultural innovation and intensification.
Pronatalist Policy
Government programs that encourage births, such as parental leave, baby bonuses, and childcare subsidies (e.g., France, Japan, Hungary).
Antinatalist Policy
Government efforts to reduce fertility, such as China's former one-child policy or India's family-planning campaigns.
Ravenstein's Laws of Migration
Generalizations that most migrants move short distances, in steps, toward large cities, produce counterflows, and that long-distance migrants tend to be young adults.
Gravity Model
Predicts interaction (including migration) between two places as proportional to their populations and inversely proportional to the distance between them.
Chain Migration
Migration in which people follow relatives or community members to a destination, creating ethnic enclaves.
Intervening Obstacle / Opportunity
A barrier (physical, legal, financial) that hinders migration, or an opportunity encountered en route that causes migrants to settle short of their intended destination.
Demographic Momentum
Population keeps growing for decades after fertility falls to replacement because a large cohort of young women is still entering childbearing age.
Replacement-Level Fertility
A TFR of about 2.1 in low-mortality countries — the level at which each generation exactly replaces itself, allowing for child mortality and the sex ratio at birth.
Cohort
A group of people sharing a demographic event in the same period, usually birth year. Cohort size drives pressure on schools, jobs, and pensions as it ages.
Population Pyramid Shape Reading
A wide base signals high fertility and Stage 2; straight sides signal Stage 4; a narrowing base with a bulging top signals Stage 5 and aging.
Sex Ratio Imbalance
An abnormal male-to-female ratio, often produced by sex-selective abortion or male-dominated labor migration, visible as asymmetry in a population pyramid.
Youth Bulge
A disproportionately large cohort of adolescents and young adults, associated with strain on employment and, in some analyses, political instability.
Demographic Dividend
A temporary economic boost when falling fertility leaves a large working-age population supporting relatively few dependents — capturable only with jobs and schooling.
A contested added stage in which fertility falls below mortality, producing natural decrease and aging, as in Japan, Italy, and Germany.
Degenerative Diseases (Epidemiological Stage 4)
Chronic illnesses such as heart disease and cancer that dominate mortality once infectious disease is controlled and life expectancy is long.
Reemergence of Infectious Disease (Stage 5)
Antibiotic resistance, poverty, and rapid global travel allow diseases like tuberculosis and malaria to resurge after appearing controlled.
Step Migration
Migration accomplished in a series of shorter moves — village to town to regional city to capital — rather than one long relocation.
Counterurbanization
Net migration from cities to smaller towns and rural areas, driven by amenity seeking, remote work, and cost of living rather than by job scarcity.
Guest Worker Program
State-managed temporary labor migration granting work but not settlement rights, as with Turkish workers in Germany or South Asian workers in Gulf states.
Remittances
Money migrants send home. For several countries remittances exceed foreign aid and direct investment, sustaining household consumption in origin regions.
Internally Displaced Person (IDP)
Someone forced from home by conflict or disaster who has not crossed an international border, and therefore lacks refugee legal protections.
Asylum Seeker
A person who has crossed a border and formally requested protection, whose refugee claim has not yet been decided.
Brain Drain and Brain Gain
Emigration of highly educated workers depletes an origin country's skilled labor while enriching the destination; return migration can reverse part of the loss.
Zelinsky's Migration Transition
Links migration type to DTM stage: Stage 2 countries generate heavy international emigration, while Stage 3 and 4 countries see mainly internal and intraregional moves.