Q sez:
>To date, no one seems to have found the 'ghost' song,
>"Bright Mohawk Valley" by Kerrigan. Its existence is doubtful,
>as noted before.

I just went over to the library and copied Edith Fowke, "'The Red River Valley' Re-Examined," Western Folklore 23 (1964), 163-171. If she didn't see Kerrigan's sheet music, she surely faked it well. Sandburg, the Lomaxes, and Spaeth all refer to it. Fowke gives the following information.

IN THE BRIGHT MOHAWK VALLEY
Words and music by James J. Kerrigan
New York: Howley, Haviland & Co.
Copyright 1896
Sheet music

Oh they say from this valley you're going,
We shall miss your sweet face and bright smile,
You will take with you all the sunshine
That has gladdened our hearts for awhile.

I have waited a long time my darling,
For those words that your lips ne'er would say,
Now the hope from my heart has departed,
And I'm told you're going away.

Chorus:
For the sake of the past, do not leave me,
Do not hasten to bid me adieu!
Oh, remain in this bright Mohawk valley,
With the fond heart that lives but for you.

Do you think of the valley you're leaving?
Oh, how dreary 'twill be when you go,
Have you thought of the heart, so lonely,
That has loved you and cherished you so.

Tell me not that our lives must be severed,
Give me back, love, the smile once so dear,
Oh! this valley would lost (sic) all its brightness,
If its fairest of flow'rs were not here.

At a brief glance, Fowke's paper seems to make an excellent case for a Canadian genesis of "Red River Valley."

Included among the testimonials is the following:

"Some years ago a friend whose home was in Montreal told me that at one time a crack Canadian regiment had been stationed in the Red River Valley locality. The officers were well thought of socially, but seem to have philandered among the Indian girls to some extent. The white girls, of course, resented this, and at a farewell ball given to the officers on the occasion of their transfer, the young lady who had composed this song rose and sang it, much to the embarrassment of the ones at whom it was aimed."

This is cited as being from the Robert Winslow Gordon collection, item no. 3133.