1. Predicting Migration: The Gravity Model and Ravenstein
Why do people migrate to specific places?

2. Objectives
Today we will be able to identify how geographers predict the size and destination of migration flows.

3. 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.

4. 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

5. 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

6. 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.

7. 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

8. Example of Migration to California

9. Share Your Findings
Share your findings from the Gravity Model Lab with your shoulder partner.
Be prepared to share with the class.

10. 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.

11. 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