There's a long history of trains (and chariots before them) as symbols in African-American songs and sermons. Two good places to read up on this are Norm Cohen's The Long Steel Rail (republished this year!) and McPherson and Williams Railroad: Trains and Train People in American Culture.

Brian

Ps I've been away from the Mudcat for a couple of months, it's nice to come back and read so many threads about music!