Reddit reviews Blues People: Negro Music in White America

It's not theory-oriented, but if you're really interested in this and related questions, I highly, highly recommend the books "Blues People" and "Black Music" by LeRoi Jones (now Amiri Baraka), which describes the evolutionary forces that led to your question. They are both shortish trade paperbacks.

Hm, maybe try Blues People? It talks about the struggle, of course, but it's positive and AA-universal.