The rioting of the 1960's sent a message that the problem of black life in America wasn't simply a problem contained to the South or one that ended with the end of de jure segregation.
It had a major role in securing a battery of policies -- affirmative action and the welfare state -- that realigned America politics.
Those policies were a compromise between two approaches and ever since the political parties have been fundamentally divided over those policies had gone too far or not done enough
One problem with sustaining support for affirmative action and welfare is that in 1970, America was a country with a white supermajority and a small black minority. Those policies were unpopular with the white supermajority at their inception and have remained so ever since.
But there was and is a large minority of white people -- educated liberals and those who take their cues from them -- supportive of those policies that has joined with 90+ percent of the black voting population to sustain them
And to preserve the permanent civil right bureaucracy ensconced in the federal government which made recourse to both administrative law and the litigation to create a power base for the maintenance of unpopular policy.
The professionalized civil rights movement was successfully able to portray opposition to its initiatives as racist, and therefore the politics of race was sublimated (liberals call it "dogwhistled") into a new idiom of opposition to the growth of the federal government
