Divisions, connections and prejudice

Most people might ask "why do Black English has a lexicon that differs from the lexicon of the American English"? Well, two explanations can be given based on the studies of Rickford and Rickford:

"One of the many fascinating features of black vocabulary is how sharply it can divide blacks and whites, and how solidly it can connect blacks from different social classes" (p.93).

The AAE vocabulary isn't accepted by the marketplace in mainstream America. Although Black English has a complex lexicon that is accessible to black people independently of the social class - something almost inexistent in standard languages - it is considered a marginal language.
One of the ways of spreading the Black English is through music, singers that are African descendents use the AAE in their songs, and only those who know or study about BE are apt to understand these songs (black music). It works as a struggle against Standard English.

Lisa J. Green:
http://books.google.com.br/books?id=bcpuNbPu-LgC&printsec=frontcover&dq=black+english&source=bl&ots=wlR4DdNvhS&sig=oRhArCdvQEftMPAqn1yrfh8Wiyo&hl=pt-BR&ei=5wGFTPT8CYL_8Abn28hV&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBQQ6AEwADgK#v=onepage&q=black%20english&f=false

Rickford

Rickford and Rickford:
http://books.google.com/books?id=MnBNCnvt2gQC&printsec=frontcover&dq=rickford+and+rickford&source=bl&ots=Ilzt2Gklw5&sig=csXBAqX5aBiKCItxaBHMLiVpUWE&hl=pt-BR&ei=kemQTMLiFcKAlAeQwqHjAQ&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBwQ6AEwAw#v=onepage&q&f=false