Iron Mountain Road, US 16A, is a scenic roadway located near Custer. Part of the Peter Norbeck National Scenic Byway, Iron Mountain Road offers some of the most spectacular views of Mount Rushmore framed in granite rock tunnels. There are three of these tunnels, each offering a different view of the mountain monument.
Iron Mountain Road also has three pigtail bridges. These corkscrew structures are engineered to curl and pass over so it negotiates the drop in elevation while still preserving the natural features of the area.
The Peter Norbeck National Scenic Byway also winds through Custer State Park and along Needles Highway before ending at Mount Rushmore National Memorial.