How about neither? While the fact that prisons are populated mostly bly blacks receives a lot of media attention, the fact that their victims are mainly blacks does not. That is a sad commentary on the failure of both, black leadership and progressive activists, who are more interested in payoffs generated by championing the cause of popular black criminals (OJ or Mumia aby Jamal) than in the welfare of black communities.
I think that high black incarceration rate has more to do with the cult of violence that grew like a cancre in black community (with the encouragement of white enertainment industry and let's-look-the-other-way attitudes of black leaders and progressive activists) than with racism or economy. A black male can gen status and peer recognition by being a violent "gangsta" (to the point that the popular expression to say that something is good is "it's gangsta") rather than becoming a professional. The black role models are "ganstas," criminals, and cheerleaders of violence and bigotry (aka hip hop singers) rather than professionals, civil leaders, or intellectuals. With such a strong encouragement of violent behavior it is no surprise that black males turn to violence in greater numbers than other ethnic groups.
The sad fact is that the so-called black leaders and progressive activists are busy exonerating this violent behavior while someone else, namely black communities, is paying the price of it.
Wojtek