Rothstein explodes the myth that America's cities came to be racially divided through de facto segregation. He makes it clear that it was the laws and policy decisions passed by local, state, and federal governments that actually promoted the discriminatory patterns that continue to this day. In the 1920s this process of de jure segregation began with explicit racial zoning, as millions of African Americans moved in a great historical migration from the South to the North. The great American suburbanization of the post-World War II years was spurred by federal subsidies for builders on the condition that no homes be sold to African Americans. The Fair Housing Act of 1968 prohibited future discrimination but did nothing to reverse embedded residential patterns