Distribution, density and growth

The essentials

World population is very unevenly distributed. A large share lives in a few regions such as East Asia, South Asia, Europe and north-eastern USA, while large areas like hot deserts, polar regions, high mountains and dense equatorial forests are thinly peopled.

Population density is the ratio between the number of people and the size of the land, usually expressed as persons per square kilometre. It tells us how crowded an area is but not how well people live.

Key points

• Geographical factors: availability of fresh water, flat plains, moderate climate and fertile soils attract people (river valleys and plains are densely populated).
• Economic factors: mineral deposits attract mining settlements; industries and urbanisation offer jobs (for example, industrial belts and big cities).
• Social and cultural factors: religious or cultural significance of a place, and social or political stability, attract people; unrest and wars drive them away.
• Density = Population ÷ Area. For example, 5 crore people on 2,50,000 km² gives 200 persons per km².
• Growth of population is the change in number of people between two points of time. Natural growth = births − deaths. Actual growth = births − deaths + in-migration − out-migration.
• A positive growth means population increases; a negative growth means it falls.
• World population grew slowly for most of history and very rapidly after the industrial revolution, mainly because death rates fell with better food supply, medicine and sanitation.
• Doubling time is the number of years a population takes to double at its current growth rate.

Exam tips

In numericals, keep units consistent: crude birth and death rates are per thousand people per year, so a difference of 20 per thousand equals a growth rate of 2 per cent.

Common mistakes

A large population does not always mean high density; density depends on area. Also, high density does not by itself mean poverty – some rich industrial regions are very densely populated.