There's so much to say about jug bands (believe it or not), it's hard to know where to begin. Why not start with my own first impression — the thing that first made me realize there's much more to the story than I thought.
Before my interest in old music, I'd thought string bands with jug accompaniment were a white thing — a really white thing. Well, don't believe everything you see on the Andy Griffith Show, I guess. I purchased a two-volume compilation of early jug bands and was surprised to find that virtually all the performers were black ... really black.
And although it's turned out that the African American experience in the South in, say, the 1920's was much more rural than I'd imagined (being a northerner), jug band music is an exception — the jug bands recorded in the 1920's were usually urban, black, and southern. A few of these records do "sound rural" to me, but to that extent, these urban bands seem to be either making fun of country life, or tapping into a nostalgia for it.
I should also mention that the level of artistry was often extremely fine.
The whole thing is ... well, not what I had expected.