Here's a thread discussion of this song from a religous site. Not sure about an origin - Helm's claim is way too late. Mac Wiseman's version was released in 1966 (if I'm not mistaken), and the song had been in oral circulation for a few decades before that. There must be a first printed copy of this out there somewhere, but we just haven't found it yet. It seems to have been localized both in Kentucky and in the Southwest, and it certainly spread by oral transmission. Amazing that a number of people still remember such a seemingly obscure song from family singing.