How did the creation of suburbs extend and reinforce economic and social segregation in the United States?

Suburbs make
their first real appearance in the United States in about the 1950s, and especially in the 1960s
as America's interstate highway system was completed, increasing peoples ability to move
themselves and goods and services more cheaply and easily. 

This came
shortly after the urban African-American population exploded during and after World War II.  I
don't think...