According to the Mary Costello Book (Climbing The Mississippi River Bridge By Bridge, Volume 2), this bridge replaced the Solway Highway Bridge. That bridge failed and collapsed in 1967 when a loaded pulp truck crossed the bridge.
That bridge was located just to the north of the new bridge. The river makes a loop, running on both sides of the highway. The old bridge crossed near the top of the loop, where the river cut diagonally across the highway. When the new bridge was built, the loop was cut off, and the new bridge was built square to the highway. One of the photos below shows the resulting straight section of river channel where the loop was cut off.
The bottom photo shows the remains of an earlier highway bridge just to the east of the tip of the loop in the Mississippi River. I am not sure if this was the location of the Solway Highway Bridge, or if this is a wooden trestle that predates that bridge.
