Marsh Concrete Rainbow Arch Bridge is a reinforced concrete through arch bridge over the Little Cottonwood River in Cambria Township, Minnesota, United States. The bridge is listed on the National Register of Historic Places. The bridge no longer carries traffic, which has since been shifted to another bridge to the east. The bridge was designed by James Barney Marsh and built in 1911, the same year in which he filed a patent for his rainbow arch design. His design features two arched ribs, one on either side of the roadway, rising above the deck. The deck is suspended from the arches by vertical risers. Drivers see the rainbow arch crowns on each side, similar to crossing a pony truss bridge. The bridge over the Little Cottonwood River is one of the oldest Marsh rainbow arches in the country. Unfortunately, as traffic flow increased and farm machinery got larger, many of Marsh's rainbow arch designs became obsolete, since they could not be widened. There are only half a dozen Marsh rainbow arch bridges remaining in Minnesota.