The Story
Iron Mountain Road (US-16A between Keystone and Custer State Park) was completed in 1933 under Senator Peter Norbeck, who chose its winding layout and pushed the project through even after engineers said it couldn't be built. Rather than a straight, efficient route, Norbeck wanted the landscape revealed gradually. Its signature features are three spiraling wooden "pigtail bridges" (designed 1932 by Cecil Clyde Gideon) that loop the road over itself on steep grades, and tunnels blasted so their openings frame Mount Rushmore's faces as you approach from the south.
Surprising Facts
→ Norbeck reportedly said he wasn't building the road to save ten minutes, but to reveal as much scenery as possible.
→ The three wooden pigtail bridges spiral the road back over itself to manage the steep grade.
→ Several tunnels were deliberately aligned so Mount Rushmore appears framed in the opening.