Births and deaths are two ways a population changes; migration is the third. Migration is a permanent or long-term move to a new home. Because it changes where people live, geographers sort migrations by where people go and why.
Key idea
Internal migration stays within one country (from a farm to a city, from one state to another); international migration crosses a border. Voluntary migrants choose to move; forced migrants are made to move or must flee. Chain migration follows family and friends who moved earlier. Step migration happens in stages (village → town → city).
- Emigration: leaving a country. Immigration: arriving in one. Net migration = immigrants − emigrants.
- Transhumance: herders moving animals between summer and winter pastures each year.
- Guest workers: people allowed into a country to work for a limited time.
- Rural-to-urban migration: the largest internal flow in most developing countries.
Why it works
Geographers sort migrations because each kind has different causes and effects. A forced move happens suddenly and often without a choice of destination, so it needs a different response than a planned move for a job. Internal moves reshape a country's own map, while international moves change two countries at once. Chain and step migration explain the routes people take: newcomers go where family can help them, or move a step at a time as they save money and gain experience.
Worked examples
Worked example: Classifying moves
Classify: (a) the Great Migration, when millions of African Americans moved from the rural South to cities of the North and West (about 1910 to 1970); (b) the Atlantic slave trade.
- (a) Within the United States, so internal. People chose to move for jobs and to escape discrimination, so voluntary, though push factors were strong. Many followed relatives: chain migration.
- (b) Millions of Africans were captured and carried across the ocean against their will: international and forced.
Answer: (a) internal, voluntary, often chain; (b) international, forced.
Worked example: Step migration
A young woman moves from her village to a market town for school, then to the capital for work. What kind of migration?
- She moves in stages, each to a larger place.
- That is step migration (and internal, rural-to-urban).
Answer: Step migration.
Common mistake
Students count refugees as voluntary migrants because they "decided to leave." People fleeing war, persecution or disaster are forced migrants: staying was not a safe choice. Also, internal migration counts as migration even though no border is crossed; it is in fact far more common than international migration.