Originally part of the Oregon Short Line Railroad, this line was a spur off of the UP at Ashton, ID, traveling southeast to Victor; there was a spur from Talbot Junction to Talbot. Today, the Eastern Idaho Railroad operates from Idaho Falls to Ashton, with part of the branch to Victor being used in and around Ashton.
From the person who explored this line:
I recently spent some time exploring an abandoned railroad bridge in eastern Idaho, not far from Jackson, WY, Yellowstone National Park and Targhee National Forest, listed on topogrpahical maps as the "Union Pacific Railroad". The abandoned Union Pacific line of which the bridge is a part runs pretty much north-south from below Victor, ID, up to above Tetonia, ID, where it starts to bend almost 90 degrees to the west-northwest. The line has been abandoned, and the abandoned properties, except for a few which reverted back to the original landowners via abandonment clauses, were brought by the state and the counties to convert to Rails to Trails. That has been completed in Victor and Driggs, and further south and east (i.e., toward Idaho Falls), but above Driggs, and particularly around Tetonia, the conversion project has not yet been completed. The rails and ties have been removed from the rail bed, and signage and fence barriers have been erected to keep vehicles off the bridge while allowing hiker/pedestrian traffic, but the trails conversion project has never been completed in this region because two or three abandoned railroad properties just north of Driggs reverted back to the original owners and the property owners are refusing to sell the property back to the state and county, thus causing an interruption in the continuity and contiguity of the trail.
Starting in Ashton, the line passed through Marysville, Grainville, Drummond, France, Lamont, and then south to Judkins, Fell, Tetonia, Talbot Junction, Driggs, Fox Creek and then ending at Victor.