Boom of housing developments outside cities in the 1950s

Financial benefits related to unemployment and home loans due to the GI Bill caused boom in the housing development outside the cities.

Explanation:

In the 1950s, the era of war was over and a new era was starting in which the veterans were returning to their homeland after World War II to start their lives as normal citizens in the American economy. To benefit the veterans, GI Bill was passed and it granted the veterans with unemployment pay for 1 year, guaranties for home loans, etc. All these factors led to the movement of people outside the cities to buy or build their own homes. These areas outside the city were sub-urban and hence were popularly called Suburbs.