This bridge was part of the Chicago & Northwestern 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. That suggests that this bridge has not operated in many years. 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.

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.