Michael,
This is Judy responding.
I wasn't out to define the whole of musical influences but to say that white appropriation is a fact of American musical history. Not the only fact. It hardly needs to be emphasized that this is a hybridized musical culture; we and others have been extremely clear about this for years.

Howard published a very interesting article called "From the Barn to the Bowery and Back Again: Musical Routes in Rural Ohio" that traces the flow of music, not only between black and white Americans but also from folk to pop and back again. Key to this article is a discussion of how the Snowdens themselves reworked a Stephen Foster song--a minstrel song--as their own anthem. Dena Epstein, in Sinful Tunes and Spirituals, recounted instances of white observers listening to slaves and thinking they were singing "slave" songs, but they were actually pop songs from the hands of white minstrel composers.