Alanabit,

You mention that you were "shocked to read of the Greensboro Massacre, which was as recent as November 3, 1979." It was certainly shocking. However, it would appear to have had little to do with the thesis that "most of the extreme violence against black folks in the South was perpetrated by the 'poor whites'." This particular conflict was not blacks vs. poor whites; it was KKK/Nazi vs. Communist/Communist sympathizer. Whether these particular Klansmen were poor, I have no idea. Those killed were, in this case, mostly white. http://images.google.com/imgres?imgurl=http://www.lib.unc.edu/ncc/ref/nchistory/nov2005/card1-lg.jpg&imgrefurl=http://www.lib.un
See also http://www.gjf.org/index.php?page=histbro
Also http://en.wikipedia.org/wiki/Greensboro_massacre

Kent