From Folk Songs of North America, compiled by Alan Lomax:

Harry Stephen, bronco-buster and cowboy poet, recalls how he composed this classic among western songs...

[...] I didn't have so much of a tune for it. In fact, cowboy songs didn't run to no regular tunes. You'd hardly ever hear cowboys singin' together much. Generally each one of um had such a different kind of a tune that each one would have to sing by himself. See, they all come from different places, they knew the songs different. So mostly they'd kind of recite things. Some of them boys couldn't carry a tune less'n they pack it over their shoulders in a gunny-sack. So they'd kindly just say it or speak it off, like I'm doin'...