The migration trend that began after World War II is known as suburbanization.
This trend resulted in millions of Americans moving from inner cities to suburbs that were located outside of the city. This helped to create the modern idea of the suburbs we know today in American society. There were several different factors that helped spark this movement including:
1) The GI Bill which allowed veterans of World War II to get low interest home loans that resulted in more individuals being able to buy a house.
2) The development of car culture- Many Americans were now able to afford vehicles, making it easier for them to live outside the city since they can drive wherever they need to go. This was a drastic change from the earlier part of the 1900's, as many people previously relied on public transportation in order to get around.