The Union Covered Bridge State Historic Site is a Missouri State Historic Site in Monroe County, Missouri. The 1871 Union Covered Bridge is a Burr-arch truss structure built over the Elk Fork of the Salt River. It was almost lost to neglect in the 1960s but was added to the state park system in 1967, the same year it was damaged by a flood. Repairs were made the next year, using timbers salvaged from another covered bridge that had been destroyed by the same flood. In 1970, it was closed to vehicular traffic. Further repairs were made in 1988, and it survived the Great Flood of 1993, only to be damaged by another flood in 2008 and later re-repaired. It is 125 feet long, 12 feet high, and 17.5 feet wide, which was just enough to admit a wagon load of hay.

The Monroe County government gave permission for bridge construction over the Elk Fork of the Salt River on April 8, 1870, after two previous bridges at the site had failed. Union Covered Bridge, named after the nearby Union Church, was constructed by Joseph Elliott in 1871 using locally sourced oak wood, opening on September 17 on the road between Paris and Fayette, and cost $5,500.

Locals raised $1,000 to preserve the bridge in 1961, but in the late 1960s, the bridge was almost a victim of neglect. In 1967, the bridge was damaged by a flood, with parts of the bridge's siding being swept away. Earlier that year, the Missouri General Assembly had passed a law to bring all remaining covered bridges into the state parks system. It was later repaired using salvaged timbers from the Mexico Covered Bridge, which had been destroyed in the same flood. Further restoration occurred in 1968, at a cost of $25,000. After serving the public for 99 years, it was closed to vehicular traffic in 1970 after it was damaged by a truck bearing a heavy load. Repairs were made again in 1988, and it survived flooding during the Great Flood of 1993.

A flood in 2008 damaged the bridge, with parts of the bridge's structure being knocked loose. As a precaution, some of the lowest siding was removed allowing the stream to flow freely through, sparing the structure the full force of the current. The bridge was saved, but the removed siding went missing. In 2011, the state of Missouri received $145,000 from the federal government to repair 2008 flood damage at Union Covered Bridge and to do work at the Sandy Creek Covered Bridge. The restoration was completed in 2019. The site is sometimes used for weddings and baptisms managed by the Mark Twain State Park. The state historic site covers 1.24 acres and contains 0.2 miles of roadway. In 2020, it was visited by 30,570 people and had a mere budget of $4,680.

The Union Covered Bridge is the only Burr-arch truss covered bridge still extant in Missouri; the other three covered bridges remaining in Missouri are examples of the Howe truss. The Burr design uses multiple king posts and an arch to support the bridge's truss. The Union Covered Bridge specifically has two arches on either side of the bridge. The design is slightly bowed upstream, which helps stabilize it in flood conditions. The bridge has been described as barn-like, and local legend claims that the appearance helped farm animals be more willing to cross it. In 1995, the interior was reported to be covered in graffiti. The components of the bridge are mainly held together with treenails, with only a few iron fasteners for additional support, while the roof is covered with wood shingles and is oriented east-west.

For 14 months during 1987 and 1988, the Missouri State Parks System and Prost Builders of Jefferson City worked together to complete a total restoration of Union Covered Bridge. A steel box truss was built through the bridge with huge counterweights on both ends. By using internal jacks, the center of the bridge was lifted 21 inches. This removed the sag from the bridge, brought all of the joints back into their original position, and removed the tension that the timbers were under, making the replacement of rotted timbers possible. A laser beam was installed to monitor progress during the lifting process. The bridge was raised approximately one inch each day. Several large timbers had rotted and were replaced. During the restoration process, the oak clapboard siding was found to be so warped that replacement was necessary. At least three different types of siding were found on the bridge, indicating the three different periods when repairs were made. On December 17, 1988, Union Covered Bridge was opened again to the public.

The bridge was listed on the National Register of Historic Places on June 15, 1970.

Located at:  N39 25.973    W92 06.154     -     WGCB #25-69-02

Photographed in May 2023