Abandoned Cottonwood River Bridge

Located just east of Sanborn, this through truss bridge carries an abandoned Chicago & North Western Railway line over the Cottonwood River. The first bridge at this location was likely a timber truss bridge, set onto timber substructures. In 1910, the bridge would be replaced by the current structure. The bridge consists of a 160-foot riveted quadrangular lattice through truss span, set onto concrete piers and approached by timber pile trestle spans on either end. The truss span uses a typical design for the era, including an A-frame portal, riveted connections and heavy built-up members. The truss span was fabricated by the American Bridge Company at the Detroit Plant, while the substructure was constructed by an unknown contractor.

Although the lattice truss design was popular in Europe, few American railroads utilized the design. While Union Pacific Railroad, the Chicago, Rock Island & Pacific Railway and a handful of eastern railroads utilized the design to various extents, no railroad constructed as many lattice truss bridges as the C&NW. Between 1878 and 1930, through trusses constructed by the C&NW nearly exclusively used this design. Although lattice trusses were not popular with American railroads after the 1880s, the C&NW relied heavily on this design, as it had proven to be resilient towards derailments and damage. The main drawback of the design was the unpredictable nature, as the structure was not statically determinant. The lattice truss design appears to have first been introduced to the C&NW by Leighton Bridge & Iron Works, which constructed some of the first iron lattice trusses for railroad use. Overall, the bridge appears to be in fair condition, with some spalling noted throughout the piers. The author has ranked this bridge as being moderately significant, due to the truss design. The bridge is currently owned by the Minnesota Department of Transportation for future railroad or trail use. The surrounding land is privately owned, and should not be accessed without permission.