Well, I'm part right and part wrong. It turns out that Kokomo Blues was recorded by Scrapper Blackwell in 1928, predating Johnson's Sweet Home Chicago by at least eight years. It seems more likely to me that Kokomo Blues was written by Blackwell, as he was raised and lived in Indianapolis, Indiana, and Kokomo, Indiana is not far north of there. Sweet Home Chicago could have been derived from Kokomo Blues, or both could have been derived from an earlier, unknown (to me) source.

While all of Robert Johnson's recordings attribute authorship to him, he obviously derived many of them from the blues tradition (this makes him in no way a less-important artist).

I will post the lyrics and vocal lines from both songs a little later and you can judge for yourselves.