http://www.bartleby.com/61/5d.html
was found after a two minute search on Google for “colonies speech american dialect” (The weird word order was to narrow the search down to only about 3,000 hits. A more planned search should do better.)
BTW, http://www.loc.gov/exhibits/treasures/images/uc06330.jpg , an image of the Dec of Indepen should yield clues to spelling thus pronounciation.
tsunamisurfer, I think you are underestimating (or omitting) the influence of African speech patterns, and the interaction (and not infrequent intermarriages) between English settlers and Indians. Both of those influences (particularly given the relative isolation of plantation or farm life in the South), could have caused a rapid acceleration in the divergence between American English and the British variety.
