Old Mill Road Bridge, Spanning Owens Creek on Old Mill Road, Rocky Ridge, Frederick County, MD

Significance: This is a well preserved example of a Pratt Through Truss bridge with pin connections. As of 1983, it is the only bridge known to survive in the United States that can be directly attributed to the Pittsburgh Bridge Company. Though built in the standard Pratt configuration (vertical compression members, diagonal diagonal tension members) the Old Mill Road Bridge is distinguished by its use of riveted floor beams rather than rolled floor beams. In line with the bridge's name there are the ruins of a mill located approximately 75 yards west of the structure. Almost certainly the bridge was built to provide access to the mill. It is also likely that the present bridge was not the first built on the site. The Old Mill Road Bridge is listed on the National Register of Historic Places.
Survey number: HAER MD-36
Building/structure dates: 1882 Initial Construction
National Register of Historic Places NRIS Number: 79001131