Whether the Missouri river folksong, which is so often mentioned, ever existed is a moot point. The only *primary* source mentioning its existence is Captain Whall in 1910:

"Originally it was a song, not a shanty, and had nothing to do with salt water. ...It must be quite fifty years since it was sung *as a song.* [Whall's emphasis.] It probably came from the American or Canadian *voyageurs,* who were great singers. ...Besides being sung at sea, this song figured in old public school collections. When very young I heard a Harrow boy sing it. That must be fifty years ago."

Whall's version is the one about the chief and his daughter: nothing flowery or sentimental there, slightly ribald actually.

Whall adds that "the usual pronunciations by American singers" were "Mizzourah" and "Shannadore."

Despite searching vast digitized collections of Google Books and HathiTrust and innumerable newspaper and periodical collections, I've
never been able to track down the "song" version that "figured in old public school collections." It should have been easy to find.

Whall makes no suggestion that the "Harrow boy" sang anything ca1860 *other* than the chief-and-daughter-firewater kind of text that Whall prints.

In any case, the boy may have learned the chantey from a relative or acquaintance who'd been at sea. That certainly appears to be likely.