If you look at the data, the difference between the social standing of blacks decades ago and now are due to the achievements of black immigrants.
http://home.uchicago.edu/~arauh/Rauh2013b.pdfThe number of black immigrants in the US quadrupled from 1980 to 2010, increasing their share of the black population from 4% to 10%. During that time period the black-white wage and employment gap widened substantially. This paper explores the extent native blacks differ from immigrant blacks. Additionally it determines in how far increased selective immigration masks an even greater deterioration in the economic condition of native blacks. In 2011, excluding black immigrants increases the white-black wage gap by 4% for men and 9% for women. It increases the employment gap by 13% and 19% for men and women respectively.