The abandoned bridge across the Powder river, west of Baker, Montana, in the far southeastern part of the state. It now serves as a driveway to someone's house believe it or not. I rode to the end of the bridge and a hundred feet or so from the end is a chain link fence with a sign on it that says "Private Property No Trespassing." There was a house just on the other side of the fence.
The bridge doesn't even look that old. You can see the new stretch of highway just beyond the dirt track visible past the end of the bridge:
View of the Powder river from the bridge:
A sign on the highway near the approach to the old bridge:
The new bridge to the south of the old bridge: