"The Plow That Broke the Plains" by Virgil Thomson?

Question:

"The Plow That Broke the Plains" by Virgil Thomson?

Public radio just played the score from "The Plow That Broke the Plains" by Virgil Thomson. One section of it sounded very familiar to me. I believe it is a cowboy song that I have heard before. Did Thomson compose it, or did he incorporate an older song into his score? If it is an older song, what is its original title?

Best Answer - Chosen by Asker: This site includes mention of Thomson's rural and folk music inspirations, but not specifically. But, this site is good reading.
http://xroads.virginia.edu/~1930s/film/l...