In 1939, Cecil Clyde Gideon gained accreditation for designing the first set of pigtail bridges in the world. Gideon was a self-taught man who trained himself in the skill sets that made him a master builder, architect, craftsman, lawman and highway designer.
Gideon's pigtail bridge design, or "spiral jumpoffs," as he called them, came to life during construction of the scenic Iron Mountain Road. The pigtail bridge design provided a balance between a safe navigable highway, preservation of the pristine Black Hills and a highway that could traverse the sudden elevation drops of the Hills. In order to maintain the aura of the Black Hills, natural materials such as local timber were used for construction.
The hairpin turns, smooth road and effortless grade change in elevation provided by the pigtail bridges, all the while being surrounded by the beauty of the Black Hills, create one of the most unique and treasured drives in the nation.
Because of the expense involved with construction, pigtail bridge designs are a rarity, and the best place to experience them is on U.S. Highway 16A heading south from Mount Rushmore National Memorial. A historical marker acknowledging Gideon's accomplishments may be viewed south of Keystone along Highway 16A.
Source: South Dakota Office of Tourism