Do we know why racial segregation occurs? In 1973, the Supreme Court said no, and in doing so, dealt a crushing blow to the civil rights movement. In Milliken v. Bradley, the court ruled that the white suburbs of Detroit could not be included in Detroit's school desegregation plan, because no real evidence existed to show that segregation in the region's schools or neighborhoods was “in any significant measure caused by governmental activity.” The justices concluded black students were concentrated in Detroit because of “unknown and perhaps unknowable factors.”
De facto segregation, it came to be called, a name suggesting a natural racial geography, which policymakers discover rather than create. The question of segregation's origins, it was implied, extended far beyond the mundanities of government and into the collective psyche of Americans. Understanding those origins required parsing the individual choices and prejudices of millions of citizens. This was a question for philosophers and sociologists, not for government officials.