“Many poor whites, however, were the derivative victims of slavery. As long as labor was cheapened by the involuntary servitude of the black man, the freedom of white labor, especially in the South, was little more than a myth. it was free only to bargain from the depressed base imposed by slavery on the whole labor market. Nor did this derivative bondage end when formal slavery gave way to the de-facto slavery of discrimination. To this day the white poor also suffer deprivation and the humiliation of poverty if not of color.”