Per Wikipedia: The first historical record of the song was by ethnomusicologist John Lomax in 1909, who recorded it as sung by an African American woman called Dink, as she washed her man's clothes in a tent camp of migratory levee-builders on the bank of the Greater Calhoun Bayou River, a few miles from Houston,Texas and the University of Houston.
Its a work in progress...
I think I've discovered an interest in what I call the "3rd voice". Singing solo typically you play an instrument like keyboard or guitar and sing along which are the 2 voices you need to perform most pop songs, but I really like the additional texture of the third voice like organ, violin, electric guitar, or in my case dobro. Which is a goddamn hard instrument. My favorite band the Milk Carton kids are really great at 4 voices: melody, bass, countermelody, harmonized melody. I don't mean that the other singer serves as a another voice, I mean that you have a voice singing alone and then when accompanied by a harmonizing voice the texture changes to create a totally unique sounding 4th voice.
Trying to sing and play dobro made me realize what a luxury frets or keys are on instruments like guitar or piano. Once you set your fingers in the right spot, just apply pressure and the design of the instrument should produce an in tune note (assuming you tuned the strings before starting). But fretless instruments like violin, trumpet, and the human voice really require a superior level of intonation because your ear has to govern whether or not your technique is producing the correct pitch. In other words having 2 separate keys you can press for C and C# really takes care of a significant amout of stress.
So then heres me trying to sing and play dobro at the same time: two "unfretted" instruments and its damn hard. But its doable I think.
Its a work in progress...