This is by far, one of the best threads I've read to date here at the 'cat. Most of it appears scholarly, at the very least knowledgeable.

Intuitively I would opt for a rowing song as it has a flexible cadence, a roll if you will, for those long strokes together that a team must make if they want to get anywhere.

Now my two cents: I remember my Dad singing this song in the mid 50's. I'm not sure but the version I remember had the words "for seven long years, I courted Saray (ser-ee) A-way you rolling river and for seven more I've tried to leave her, A-way, I'm bound a-way across the wide Missouri". My Dad and his brothers were all great singers as was my Grandfather (beautiful tenor voice) and I'm told that my Great Grandfather was also a singer so there is a musical tradition that goes back quite far.

As to the origins of this most lovely song, I'll stay tuned. Thanks all.