Union Covered Bridge State Historic Site in Monroe County, Missouri, is maintained by the Missouri Department of Natural Resources as a state historic site to preserve the Union covered bridge. The bridge was built in 1871 across the Elk Fork of the Salt River as a link in the Paris-to-Fayette road. Its name comes from the nearby Union Church. In 1968 a partial restoration was completed using materials from the Mexico Covered Bridge which was destroyed the year before by flood waters. In 1970 the Union bridge was closed after structural timbers were damaged by overweight trucks. A total restoration was completed in 1988. The bridge was entered on the National Register of Historic Places in 1970.
The bridge is a 120 foot (36.6 m) long Burr Arch span that is 17 feet 6 inches (5.3 m) wide and 12 feet high (3.7 m). Joseph C. Elliot built the bridge in 1871 from local oak. It is sided in clapboard and uses wood shingles. Two earlier uncovered bridges at this site were replaced in turn due to deterioration.
Some siding was removed as an emergency measure in 2008 when the bridge was threatened by severe flooding. Removal of the lowest siding allowed the stream to flow freely through the understructure of the bridge, thus sparing it the full force of the current. The bridge was saved, but the removed siding is still missing while funds for repair are sought.