What makes you think that blacks are a unified community with no class distinction, holding uniform political views?
It is not really about skin color or cultural heritage but about class. The skin color happened to be the manifestation and the marker of class divisions in the US. It is not that there are inequalities because there are racial divisions in the US, but the other way around - racial divisions are created by class divisions. If there were no blacks in the US, the class divisions would still be there, only manifested differently, perhaps by ethnicity (Eastern European? Mediterranean? Asian? Latino?) perhaps by residence (North vs South? Urban vs rural?) perhaps by look (slim vs obese, blonde vs dark or perhaps having the "wrong" shape of the nose), or perhaps simply by possession.
Wojtek