The Black community largely recovered from slavery by the 20th century (with intact families and two-parent households). It was the welfare state that began with FDR and snowballed with LBJ that has been their undoing (which sped up the absence of fathers).
WELFARE - The Legacy of F.D.R. - TIME
http://content.time.com/time/specials/packages/article/0,28804,1906802_1907092_1906939,00.html
When the Vietnamese came here it took them about 5 years to buy nail salons and to corner the market on hardwood flooring. The Chinese opened restaurants, the Indians bought 7/11's and motels. It shouldn't take blacks 150 years to pull themselves up. They already knew the language. In fact, they spoke better English 20 years ago then they do now.