Population Geography: Growth, Density, and Distribution

Population geography asks not just how many people live somewhere, but where, and why there rather than somewhere else. Population distribution across Earth is wildly uneven: dense clusters sit in East Asia, South Asia, Europe, and eastern North America, while vast areas -- deserts, high mountains, polar regions, dense rainforest interiors -- hold very few people. Population density measures this by dividing a place's population by its land area, usually as people per square kilometer.

A population pyramid graphs a place's population by age and sex, and its shape tells a story. A wide base that narrows quickly toward the top shows a young, fast-growing population -- typical of many developing countries with high birth rates. A pyramid shaped more like a column shows an older, slow-growing or shrinking population -- typical of many highly developed countries with low birth rates. The demographic transition model describes how a country's birth and death rates typically change as it develops: rates start high and roughly balanced (slow growth), then death rates fall first while birth rates stay high (rapid growth, as medicine and sanitation improve faster than family habits change), then birth rates fall too (growth slows), and finally both rates settle low (slow growth or decline).