McGrath-- I have read that the term came from a particular early tune in early traveling minstrel shows, which featured a song/dance combination, and the title of which was *Old Zip Coon*. It is quite similar to *Turkey in the Straw*, and apparently most of the minstrel shows which traveled through the South featured this number. As early as 1837, the song had become popular enough to be widely printed and circulated in a collection of minstrel pieces which included another popular song associated with the minstrels, called *Jim Crow*. While this may not make a strong case for the origination of the term as applied, I believe that it explains the spread of its use.