Iron Mountain Road, US-16A

Driving

by Plot Along: Heartland

Iron Mountain Road is the 17-mile stretch of US-16A between Custer State Park and Mount Rushmore, a Peter Norbeck design and one of the most clever scenic roads anywhere. Norbeck packed it with 314 curves, 14 switchbacks, three one-lane tunnels, and three "pigtail" bridges: wooden spiral overpasses that corkscrew the road back over itself to lose elevation in a tight space. The tunnels are the real trick. Each was blasted at an angle to frame the carved faces of Mount Rushmore dead-center as you approach, so the memorial appears in the round opening like a picture.

Norbeck told his engineers to build the road "to fit the topography" and to drive it at no more than 20 mph. It was never meant to be efficient, only beautiful.

Fully paved and open year-round, though snow and ice can close the high curves in winter. The tunnels are narrow, so oversized vehicles should check clearances. Drive it northbound for the framed Rushmore reveals.

Learn more: en.wikipedia.org

1
Bison Lookout
The southern start of Iron Mountain Road, a parking overlook in Custer State Park near the US-16A / SD-36 junction, where the road begins its climb toward the namesake summit and the pigtail bridges.
2
Iron Mountain
The high point the road is named for, near the wooden 'pigtail' spiral bridges that corkscrew the highway back over itself. Norbeck's trick for shedding elevation in tight country.
3
Doane Robinson Tunnel
One of three tunnels blasted at an angle so that the faces of Mount Rushmore appear framed dead-center in the rock opening as you drive toward them. It's named for the historian who first proposed carving the Black Hills.
4
Mount Rushmore
The northern destination, reached by the parking ramps at the memorial: Gutzon Borglum's 60-foot granite portraits of Washington, Jefferson, Roosevelt, and Lincoln, the views the whole road was engineered to set up.

Bison Lookout

Iron Mountain

Doane Robinson Tunnel

Mount Rushmore