Here's an interesting article I found while googling. The author wrote a book about spending a year shopping only at black businesses.
MA: Oh, the worst thing was what we learned about economies in black neighborhoods. We assumed, just like other little ethnic enclaves like Little Italy or Greek Town or Chinatown, that for predominantly black neighborhoods all the black businesses there would be owned by the local people. But easily over 90 percent of the businesses on the West Side—and it's the same way all over the country—are owned by people who are not black and do not live in that community. So it's not a "buy local" thing, because these folks set up shop in the black community, sell their wares, make their money, hardly ever employ the local people there—and they put the steel bar over the door, pack up at 6:30, get in their car, drive to their suburb, and take that money with them. And that was the whole reason that these communities suffer the way they do: The everyday exit of the wealth in those neighborhoods directly leads to social crises there.
So I'm literally walking around and talking to people, "Is there a black-owned restaurant, or a black-owned dry cleaner?" and folks are looking at me like I'm insane. And if I didn't know this, I'm sure that folks outside the black community don't have this as part of their reality or part of their picture for black America. When we talk about black people, the black situation, problems in the black community, you know, we start with, "Black kids are least likely to graduate from school; black unemployment is four times higher than the national average," all these numbers. But why can't we include that over 90 percent of businesses in the black community are not owned by black people or local residents? If we were to add that to the conversation, maybe folks would say, "Oh, well no wonder things are so bad there," and start thinking about things in a different way instead of allowing those awful numbers to be a reflection of our propensities. Why is it that my people are just supposed to be the perpetual consumer class, and everyone else is supposed to benefit from our money?
http://www.motherjones.com/media/2012/02/maggie-anderson-our-black-year