Handy song “Yellow Dog Blues”; if not, there are links to a couple of performances at the Mississippi Blues Travellers page Where The Southern Cross The Dog – Moorhead, Mississippi, one of those maniacally detailed investigations of historical/cultural backwaters that so appeal to me. Most of it is about the music, but I’ll quote the part that goes into the etymology of “Yellow Dog”:The Yazoo Delta RR was nicknamed the “Yellow Dog.” W.C Handy gives a different explanation for the origin of the nickname “Yellow Dog” in Chapter 6 of his autobiography. was christened The Yellow Dog. The story was circulated and the idea spread until one branch of of the Yazoo Delta was known as the North Dog.