The South Salem Covered Bridge is a historic covered bridge in northwestern Ross County, Ohio, United States. It was built in the 1870s and has been designated a historic site because of its well-preserved historic engineering. Since its construction, it has carried Lower Twin Road over Buckskin Creek in Buckskin Township. The bridge is a wooden Smith truss bridge, built in 1873 according to a design patented by Ohioan Robert Smith in the late 1860s. Eight wooden panels wide, it rests on stone abutments and is covered with a metal roof.
In 1975, the bridge was listed on the National Register of Historic Places because of its historically significant engineering. Key to its significance is its unique status: all other covered bridges in Ross County have been destroyed, leaving the South Salem bridge standing alone.