Predicting Migration: The Gravity Model and Ravenstein Why do people migrate to specific places?
Objectives Today we will be able to identify how geographers predict the size and destination of migration flows.
Distance on Migration • Distance Decay – The tendency for migration, or any other spatial interaction, to decrease with distance. • Distance creates more drag or friction on movement. • People are unlikely to move to faraway places they know little about.
Migration Streams • When groups migrate, they tend to move in well-defined channels from specific origins to specific destinations. • They result from information flows between origins and destinations. • Letters, telephone calls, return visits from individuals. • Earlier migrants assist newcomers with employment, housing, and adjustment. • A migration counterstream is the flow of people back to their place of origin
Examples of Migration Streams in the United States • New York and New Jersey to Florida • The midwestern states and California • Employment migration streams • Immigration to United States from nations of origin to immigrant communities or enclaves. • Familiar language, food, music, and religious institutions. • Cuba to Florida • Mexico to southwest • Ireland to Boston
Can we predict migrant flows? Why is it important to make migration predictions? Important in making accurate population projections and monitoring regional economic health an quality of life. Some predictions merely look at past migration trends. Looking at the geography of migration can give us a more detailed look.
The Gravity Model • Based off of Isaac Newton’s formula for gravitational attraction between two celestial masses. • Newton’s law has been adapted to the social sciences to estimate the spatial interaction or movement between any two places. • William J. Reilly, 1931
Share Your Findings Share your findings from the Gravity Model Lab with your shoulder partner. Be prepared to share with the class.
Ravenstein’s Laws of Migration • Every migration flow generates a return or counter-migration • The majority of migrants move a short distance • Migrants who move longer distances tend to choose big-city destinations • Urban residents are less migratory than inhabitants of rural areas • Families are less likely to make international moves than young adults • An inverse relationship between the volume of migration and the distance between source and destination • The number of migrants to a destination declines as the distance they must travel increases.
Other Key Ideas • Step migration – The series of stages that migrants go through to reach a final destination. • Rural Brazil to a village to a town to Rio de Janeiro. • Chain Migration – Flows along and through kinship links. • Immigration Waves – Swells in the number of migrants to a destination • Intervening Opportunity – Opportunities along the migration stream which may keep the mogrant from actually reaching the final destination. • Internally Displaced Persons (IDPs) – People displaved within their own country • Katrina