Framing

Generally Framing is a state of mind that's been molded into a given perception of something.  In this case it is African Americans. What events have happened for the world to generally give the stereotype of insignificance when compared to the Caucasian race?  What events have occurred that labeled us as gang bangers, thieves, and criminals?  The question that I feel is most important is; who embedded these ideals?  I normally don't like to use Wikipedia but it defines Framing perfectly:  http://en.wikipedia.org/wiki/Framing_%28social_sciences%29              Is there anyone out there who can answer these questions?