Etymology of 'white trash'

I was reading through a book of Lovecraft’s stories, when I came upon the phrase “white trash” being used, in the same context it is now days. I can’t remember the exact story, but I thought it was odd that the phrase was actually used close to a hundred years ago. Does anyone know the earliest example of “white trash” being used in literature?

http://www.etymonline.com/t6etym.htm