Barbara Shaw is always gracious, Jim. Thanks to both of you for refreshing this thread. Now that I have Spotify, I can go straight to the song and take a listen. The version I found is from a group called "Boiled Buzzards." I didn't find a recording from Tom. T. Hall or Marshall Wilborn.
But I dunno about the truth of the song. I live along the Transcontinental Railroad in the Sierra Foothills. The railroad is visible from our yard. I always wave when I'm close enough to be seen, and the engineers always wave back.
-Joe-