Racism, always a national fact, not just a southern one, emerged in northern cities, as the federal government made concessions to poor blacks in a way that pitted them against poor whites for resources made scarce by the system. Blacks, freed from slavery to take their place under capitalism, had long been forced into conflict with whites for scarce jobs. Now, with desegregation in housing, blacks tried to move into neighborhoods where whites, themselves poor, crowded, troubled could find in them a target for their anger.

….

In Boston, the busing of black children to white schools, and whites to black schools, set off a wave of white neighborhood violence. The use of busing to integrate schools – sponsored by the government and the courts in response to the black movement – was an ingenious concession to protest. It had the effect of pushing poor whites and poor blacks into competition for the miserable inadequate schools which the system provided for all the poor.

1970s. From Howard Zinn’s A People’s History of the United States