Read an interesting article on this subject last night. They have been doing a study of the Confederados in Brazil and their accents and they are concluding that the Southern Accent is more of a manifestation of Post-CW America because the accent of the Confederados is not pronounced at all. These researchers were theorizing that the American accent was more homogeneous before the war than previously thought. For example, the Confederados pronounce pin and pen differently but Southerns today tend to pronounce them as homonyms. I have to admit I pronounce those two words the same (drives my Yankee wife nuts, but then I don't eat bannaners like she does).