The CQA Four Mile Bridge spans the Big Horn River in Hot Springs County, Wyoming. The bridge was erected in 1927-28 by the Charles M. Smith Company and spans 175 feet (53 m) with a total length of 295 feet (90 m). The rigid 7-panel Pennsylvania through-truss was nominated for inclusion on the National Register of Historic Places as one of forty bridges throughout Wyoming that collectively illustrate steel truss construction, a technique of bridge design that has become obsolete since the mid-twentieth century. The bridge rests on concrete piers and abutments and is approached by two Warren pony trusses.