CS - without disregarding your last comment! another example - relates to Amos' post too.

John Lee Hookers Boogie Chillen. First heard it played in the background of the Blues Brothers film and found it utterly mesmerizing. Deceptively simple (one chord boogie!), but I've never, ever heard anyone play it better than JLH on the 1948 recording. I'm not sure if it counts as alternative Americana or not but it's far away from the mainstream and an example of American music that I love.

The Dock Boggs track has a similar effect btw.

Hope that helps!

Pete.