PERFECT!
The builders allowed for the rapid flow of the river on the North side, but below the lock, that is normally calm water. However, when they drain the lock, the bridge pier would be subjected to scouring.
If this happened, the East side of the bridge pier (down on the first image on 1674, would be on the down flow side and would be the first to drop.
If the down-flow side dropped, it would cause the twisting movement of the bridge towards the East, and cause the North side of the bridge to move West. This is what we see in the images.
The Mississippi river flows from West to East at this location. The lock is on the South side of the river.
The major portion of the city of Minneapolis is South of the river, if you are using satellite images.
This bridge would be located just North and East of the center of Minneapolis.