The South Dakota Department of Transportation constructed the Keystone Wye Bridge as part of a project to improve vehicle access to tourist destinations in the Black Hills. The undertaking included converting U.S. 16 into a four-lane highway between Rapid City and Keystone, and building a new interchange for U.S. 16, a major east-west highway across the state, and U.S. 16A, one of the scenic highways through the Black Hills. The new interchange was a three-level bridge constructed of glue-laminated timber. The uppermost structure is an arch bridge supported by three 66-foot, single-hinged arches built of Douglas fir and connected with steel braces and fittings; the second level is a beam bridge; and the main level consists of the highway itself. The road decks are supported by steel beams and the entire bridge rests on concrete footings. The bridge was officially dedicated in October 1968.
Department of Transportation. Keystone Wye. Custer, SD: Nauman Films, Inc., 2013. Film.