"The United States grew wealthy on the back of American slaves."  

Correct. And by 1965, America had begun rectifying the evil effects of that institution.  Most black families were intact, law-abiding and on the way out of poverty. By 1978, blacks had been granted rights under affirmative action, sealed into law by Bakke. Somewhere along the way, a large segment of the black population got screwed again by white intellectuals, most of them women, who taught that the traditional family unit wasn;t necessary, and that having a responsible man around the house wasn't necessary. From black separatists and other like-minded groups, they learned that working hard in school was "white." Ironically, this happened while the average American parents were wishing their children were more like Asians when it came to discipline and school work. There's a reason for the disparity between Asians and whites in school success, and the gulf between those two and blacks.  It's not skin color.