This bridge was part of the Chicago & North Western mainline across the state of Minnesota. A new route was built south of the Minnesota River between Mankato and New Ulm, reducing the importance of this line. The C&NW eventually abandoned this line, with the exception of a small spur that runs south out of New Ulm, across the river, and about 2 miles past the river. It serves a very large rock quarry operation.

This is the original 1880 structure, which makes the Redstone Bridge one of the oldest bridges in the state of Minnesota that is still in operation. The bridge appears to have had some recent repair work done to stabilize the piers. In fact, the swing span appears to be bolted into the closed position suggesting that this bridge has not been opened in decades. The bridge opening mechanism is purely manual. A bridge tender would insert a crank into a slot in a gear, and that gear turns another gear, which moved against a large ring gear set into the top of the pier. This gearing allowed the tender to move the heavy swing span with very little physical effort.

The Redstone Bridge is very similar to the former swing bridges located at Chaska (for the Hastings & Dakota Railroad) and Saint Peter (also for the Chicago & North Western). The only remains of the Chaska bridge is one abutment, while the stone piers for the Saint Peter bridge are still standing. The piers for the Saint Peter and the Redstone Bridge were nearly identical. The piers on the Redstone Bridge have since been encased in concrete to prevent them from crumbling. The swing span is type known as a center pin pivot bridge. This type is built as a single truss that turns on a set of wheels that follow a metal guide ring. Due to being a single truss, they tend to be hard to balance. In contrast, more modern swing spans are built from two trusses that are joined over the pivot point.

Based on measurements made from the ruler tool in Google Earth, the bridge appears to be 866 feet long overall. That includes 466 feet of steel truss structure arranged as a 127 foot truss span, a 200 foot swing span, and another 127 foot truss span. The west end continues as a 400 foot long timber trestle.

The Redstone Bridge was named after the small town of Redstone which once existed near the southeast end of the bridge.

The two photos above and below are views looking towards the south face of the Redstone Bridge from the east bank of the Minnesota River. The photo above is an overview of the river crossing, while the photo below is a closer view of the swing span.

These two photos are views from the east riverbank on the downriver south side of the bridge. The photo above is a close view of the swing span, while the photo below shows the entire river crossing. Note the trestle crossing the river flats on the west side of the river.

These two views are from the east bridge portal. The photo above is looking down the length of the river crossing, while the photo below is a view from the southeast corner of the structure. Note that there are 4 rails on the tracks rather than two. The inner set of rails are guards to prevent a derailed train car from piling into the bridge or falling into the river.

The photo above is a detail view of the truss structure at the abutment on the east end of the railroad bridge. The photo below is a view from under the easternmost truss structure looking west towards the fixed pier at the east end of the swing span.