Oh, here are the introductory notes from SING OUT!:

Composed originally in the waning days of World War II, this song was a popular folk-style appeal for the United Nations. Leadbelly was enthusiastic about the song and sang it constantly...The composers are a distinguished team. Earl Robinson, many of whose songs have appeared in these pages, is composer of "Joe Hill," "Ballad for Americans," "Lonesome Train," "House I Live In," "Black and White," and scores of other works. E. Y. "Yip" Harburg is best known for the libretto to "Finian's Rainbow." He is also author of the lyrics to the songs in the film version of "Wizard of Oz," and lyricist for that depression calssic, "Brother Can You Spare A Dime?" Harburg and Robinson also collaborated on "Free and Equal Blues."

Fasinating!
Charley Noble