Found the following info' FWIW:

In the early 1800's, Natchez "Under the Hill" in Mississippi was a gathering place for the "Keel-boatman" bringing goods and supplies down the Mississippi River on their way to New Orleans. Each boat had its own "champion" fighter and when two boats met , it was the custom for these "Champions" to fight for the honored title of "Cock of the Walk" and "Best of the Best."