Here's a photo taken on July 03, 1989, THIRTY-THREE YEARS AGO, of High Iron Travel's
Explorers III chartered train running along the Missouri River on its return journey from Ft. Benton to Great Falls. This line was used into the 1950s or 60s by Great Northern's
Western Star passenger train when it deviated off the mainline to serve Great Falls. GN and BN ran a RDC car over this line from Havre to Great Falls until the start-up of Amtrak. There is now an abandoned middle segment of this line, with Ft. Benton being at the western end of the abandoned segment. As we see here, the line ran close to the edge of the Missouri River for many miles and became a maintenance headache at certain locations when the cliffs started crumbling out from under the track.
Both GN and Milwaukee built impressive stations in Great Falls, both of which survive today. I don't believe the Milwaukee ever ran much more than a glorified doodle-bug or shuttle train to and from their mainline at Harlowton.