It is indeed the entry of this ancient into the aural lexicon of the American frontier expansion as seen from today that becomes the point of pursuit. It's Hollywood's back-up American anthem. Ken Burns can't go out of the house without "Shenandoah". Every third-grade dulcimer playing teacher forever MUST have Shenandoah. But why the Western trend? Why does it sound so American Western. I suppose because the song simply dwells on great distance over water. Any distance, any water.
With no doubt at all in it's origination as a chanty, and a flexible, durable one at that, the melody and whatever words laid on top of it over the years made it well past (and perhaps before) the c.1820 printed on a liner sleeve.
It's a song we can make up our own words to and find the product [if a chanty] still faithful:
Pull up the sails, ye strong young laddies Away, Away, let's be away 'Cross the great MacAughney. [for example]
It's when the word "Missouri" got in there that the mystery really gets under way.
At this point in research I can say a few things for sure. 1. Yes, there's no doubt we have a chanty. 2. 'Shenandoah' is MOST likely utterly irrelevant: not a word in the song, a figure nor the title itself bear "Shenandoah" spelled just such. Shen* is not the beloved object of the song, a product of Shen* has the singer's eye.
I look forward to seeing additional info on this at the Mudcat.
Thanks for your tremendous input here, esp Barry Finn. I am getting more info daily and will be happy to share with those of interest. I will post the final "conclusions" when they're sifted.