How Is Population Size Affected by Migration?
The population of an area is affected by movement of people into (immigration) and out of (emigration) that area.
Most countries influence their rates of population growth to some extent by restricting immigration.
Only a few countries -- chiefly Canada, Australia and the US -- allow large annual increases in population from immigration.
International migration to developed countries absorbs only about 1% of the annual population growth in developing countries.
Population change for most countries is determined mainly by the difference between their birth rates and their death rates.
Migration within countries, especially from rural to urban areas, plays an important role in the population dynamics of cities, towns and rural areas.