The Sixes Road Bridge is the only two-span historic remaining on the Monocacy River owned by Frederick County. Its 240 feet length makes it is the longest historic bridge in the county. It is located in the northeastern part of Frederick County down stream from Bullfrog Road Bridge. In this section of Frederick County the Monocacy River forms the border with Carroll County, Maryland. The bridge was built in 1915 by the York Bridge Company. The design is Pratt truss. The bridge was rehabilitated in 1995.
Info from Frederick County Dept of Highways and Transportation.