Blacks have not assimilated as well as they should have by now because they have been kept on welfare plantations and because their “civil rights leaders” fear that, if they do assimilate, they will no longer be a reliable voting bloc, but, rather, will begin to vote more on issues other than race and handouts.
There’s a vid around here somewhere of Obama talking about how it threatens the Rats’ ability to elect blacks if blacks move from inner city [plantations] into the suburbs.
I think it may be this one:
http://www.freerepublic.com/focus/f-bloggers/2115374/posts
It's been that way since the 60's. Before that, it was segregation which prevented Blacks from assimilating.