The lyrics, "I'm going to where the southern crosses the yellow dog" comes from a southern man who was found in a train station very late at night making up a Blues song as he went. He kept repeating the lines, "I'm goin' to where the southern crosses the yellow dog," which made no sense to the listener, who then asked the meaning of it. The old man responded, "it's an intersection of the the southern railroad tracks and the yellow dog railroad tracks, and that's where I'm headed, home." Very simple meaning but beautiful at the same time, and at that moment the man who heard him decided to produce rural Blues artists. The line represents a southern rural Bluesy ideal, and Dylan liked the Bluesy south, which is also what inspired his album Highway 61 Revisited
because it led directly from Minnesota down to the delta south.