AP Human Geography – Unit 2 Comprehensive Notes

Population Distribution

• Definition: pattern of human habitation across Earth; addresses where people live.

• If evenly spread, each person would have ~2 U.S. football fields of space.

Physical Factors (WHY people cluster or avoid places)

Climate

• Harsh climates (too wet, cold, dry, or hot) discourage dense settlement.

• Most humans prefer mid-latitudes (≈30°–60° N/S) for mild temperatures and adequate precipitation.

• Example: Australia—population hugs temperate coasts; interior desert is sparsely populated.

Landforms

• Lowlands attract settlement: easier construction & agriculture.

• Mountains = sparse (cold, thin air, limited food); exception: equatorial highlands—cooler than lowlands, thus more settled.

Water Bodies

• Historic magnet for settlement—rivers, lakes, oceans provide drinking water, irrigation, transport, trade.

Human Factors

Culture

• Attachment to ancestral/holy lands (e.g., Jews & Muslims to Israel/Palestine).

Economics

• Jobs/resources draw people; scarcity pushes them out.

• African slave trade & 19th-c. European migration to U.S. driven by economic motives.

History

• Past patterns influence current distribution (e.g., >50% of Black Americans still in South due to slavery legacy; ~50% of Asian Americans in West due to earlier Asian immigration).

Politics

• Unwanted regimes push; welcoming ones pull.

• 19th-c. Europeans escaping tyranny → U.S.

• Khmer Rouge (1975) forcibly relocated Cambodians from Phnom Penh to countryside.

Population Density

• Definition: how many people occupy a given land unit.

• Distinct from distribution (where vs. how many).

Three Calculations

Arithmetic Density

• $D_a=\frac{\text{total population}}{\text{total land area}}$ (includes uninhabitable land)

• Taiwan: one of the world’s highest overall densities, but ¾ of people cram onto ⅓ of land—shows limitation of arithmetic figure.

Physiological Density

• $D_p=\frac{\text{total population}}{\text{arable land area}}$

• Measures pressure on farmland.

• UAE (2020): arithmetic ≈312 ppl/mi²; physiological >6 000 ppl/mi² because only ~0.5% is arable.

Agricultural Density

• $D_{ag}=\frac{\text{number of farmers}}{\text{arable land area}}$

• Low $D_{ag}$ = mechanized, wealthy farming.

• High $D_{ag}$ = lots of subsistence farmers.

Why Density Matters (4 Processes)

1. Political – Census shifts legislative seats (e.g., U.S. House reapportionment).

2. Economic – Guides private & public investment (stores, roads, bridges).

3. Social – Determines service placement (schools, hospitals).

4. Environmental – Linked to carrying capacity; estimates range ≈ $5\times10^8$ to $1\times10^{12}$ humans, complicated by unequal resource use.

Population Composition

• Describes characteristics such as age, sex, race.

Age Structure

• Grouped in cohorts (e.g., 0–4, 5–9).

Dependency Ratio

• $DR=\frac{\text{Pop}<em>{0-14}+\text{Pop}</em>{65+}}{\text{Pop}_{15-64}}\times100$

• High DR = heavy burden on workers; low DR = lighter burden.

Sex Ratio

• Global ~101 M : 100 F.

• Europe ~95 : 100; China ~110 : 100 (legacy of One-Child Policy).

Population Pyramids

• X-axis = % male (L) & female (R); Y-axis = 5-yr cohorts.

Shapes & Meanings

• Wide base / triangle – rapid growth (e.g., DR Congo).

• Narrower triangle – slow growth (e.g., China).

• Column – stable (e.g., USA).

• Inverted pyramid – decline (e.g., Germany).

Population Dynamics

Fertility Measures

Crude Birth Rate (CBR)

• Births per 1 000/yr.

Total Fertility Rate (TFR)

• Avg. children per woman (15–49).

• Replacement ≈ $2.1$

• Europe (2020): $1.5$ (decline); Africa: $4.3$ (growth).

Mortality Measures

Crude Death Rate (CDR)

• Deaths per 1 000/yr (global ≈8; 1960 ≈13).

Infant Mortality Rate (IMR)

• Deaths <1 yr per 1 000 live births.

Life Expectancy

• Avg. years at birth (wealthy nations ≈80; developing ≈50).

Growth Metrics

Rate of Natural Increase

• $RNI=CBR-CDR$ (per 1 000).

• Example: CBR 20 – CDR 10 ⇒ $RNI=10$ → growth.

Doubling Time

• Years to double at current growth (Ethiopia ≈27 yrs; USA ≈233 yrs).

Influencing Factors

• Social/Cultural – gender roles, education, contraception.

• Political – pro-/anti-natalist laws (e.g., China One-Child).

• Economic – prosperity ↑ babies (baby boom); recessions ↓ babies.

Theoretical Models

Demographic Transition Model (DTM)

1. Stage 1: High Stationary – high CBR & CDR; pre-industrial; pop stable.

2. Stage 2: Early Expanding – high CBR, falling CDR; industrialization; pop explosion.

3. Stage 3: Late Expanding – falling CBR, low CDR; slower growth.

4. Stage 4: Low Stationary – low CBR ≈ CDR; stabilizes; fully industrial.

5. Stage 5: Natural Decrease – CBR < CDR; aging & decline (e.g., Japan, some EU states).

Epidemiological Transition Model (ETM)

1. Famine/Pestilence – high deaths from infectious disease, famine, animals (e.g., Black Death).

2. Receding Pandemics – sanitation/medicine ↓death; life exp. 30→50.

3. Degenerative & Human-Created Diseases – chronic illness (heart, cancer).

4. Delayed Degenerative – medical advances delay onset; highest life expectancy.

5. Re-emergence of Infectious Disease – antibiotic resistance; life exp. falls.

• Critiques: oversimplifies, ignores poverty/regional variation.

Malthusian Theory

• Thomas Malthus (1798): pop grows exponentially; food arithmetically; predicts famine.

• Reality: technology (mechanized farming, fertilizers) expanded food supply—proved overly pessimistic.

Government Policies & Women’s Roles

Policy Types

Antinatalist

• Curb births (e.g., China One-Child 1979–2015).

Pronatalist

• Encourage births (longer parental leave, free childcare).

Immigration

• Open or restrict flows (post-WWII Europe invited labor).

Women & Demography

• Education – “More books, fewer babies”; educated women postpone/limit births.

• Family Planning – access to contraception ↓TFR.

• Employment – career opportunities delay marriage/childbearing.

• Elevated status ↓IMR & shapes migration (women dominate internal moves; men dominate international per Ravenstein’s Law 6).

Aging Populations (low TFR + long life exp.)

• Political – older voters sway policy (e.g., Social Security in U.S.).

• Social – Increased eldercare need; shift to nuclear families increases nursing home demand.

• Economic – shrinking tax base; high DR; stress on pensions (U.S. Social Security projected depletion 2031).

Migration Fundamentals

• Immigration = into; Emigration = exit.

• Decision driven by Push (negative) & Pull (positive) factors, usually mixed.

Intervening Concepts

• Intervening Obstacles – barriers (cost, visas, mountains).

• Intervening Opportunities – unexpected chances causing migrants to settle en route.

Factor Categories

1. Cultural – persecution; Partition of India (Hindus ↔ Muslims).

2. Demographic – Lack of services/jobs in dense cities or sparse rural areas.

3. Economic – employment (Bracero Program: 4 M Mexicans to U.S. WWII era).

4. Environmental – disasters (Katrina 2005) or climate preference (retirees → Florida).

5. Political – war (Syrian Civil War >5 M refugees).

Forced vs. Voluntary

• Forced – slavery, genocide, war refugees, Internally Displaced Persons (IDPs).

• Voluntary – seven sub-types:

  1. Transnational – maintain ties; send remittances.

  2. Transhumance – seasonal/nomadic.

  3. Internal – within same country; usually short-distance.

  4. Chain – follow earlier migrants (Irish to U.S.).

  5. Step – series of stages with stops.

  6. Guest Workers – temporary labor visas (e.g., Braceros).

  7. Rural → Urban – tied to industrialization.

Effects of Migration

Political

• Redistribution of power (U.S. Sunbelt gains seats).

• Native backlash → restrictive laws (Chinese Exclusion Act 1882).

Economic

• Destination: labor supply, fill low-wage sectors; lower dependency ratio.

• Origin: job openings; BUT brain/worker drain can slow growth.

• Remittances: >$6.3\times10^{11}$ USD (2022) bolster origin economies.

Cultural

• Destination: cultural diffusion (Mexican cuisine mainstream in U.S.).

• Origin: families gain financially, but social fabric may strain (parental separation ↑ dependency ratio).

Key Equations & Numbers to Memorize

• $D_a=\frac{P}{A}$ (Arithmetic Density)

• $D<em>p=\frac{P}{A</em>{\text{arable}}}$ (Physiological Density)

• $D<em>{ag}=\frac{\text{Farmers}}{A</em>{\text{arable}}}$ (Agricultural Density)

• $RNI=CBR-CDR$

• Replacement TFR ≈ $2.1$

• $DR=\frac{\text{Dep.}}{\text{Work}}\times100$

Selected Stats

• UAE Dp>6\,000/mi², $D</em>a\approx312$/mi².

• Sex ratios: World 101:100; Europe 95:100; China 110:100.

• Global CDR ↓ 13→8 per 1 000 (1960→present).

• Ethiopia doubling ≈27 yrs; U.S. ≈233 yrs.