Getting Oriented
Iron Mountain Road runs north-south between US-16A's southern junction with SD-89 in Custer State Park and the Keystone Wye, where it joins US-16 west of Mount Rushmore. Custer State Park manages the southern half; the Black Hills National Forest manages the northern half. The road is the only route through Custer State Park that doesn't require a park entrance fee, provided drivers don't stop.
Trail Overview
Seventeen miles of two-lane pavement, point-to-point. Three one-lane tunnels punctuate the route: Doane Robinson Tunnel, Iron Creek Tunnel, and Scovel Johnson Tunnel. All three sit below 12 feet, 4 inches in clearance and 8 feet in width, which excludes most RVs and large pickups with rooftop tents. The pigtail bridges are wood-truss spirals that route the road over itself to manage the elevation drop. Drive time is about an hour without stops.
Points of Interest
- Doane Robinson Tunnel. Northernmost of the three, named for the historian who first proposed Mount Rushmore. Aligned with the memorial.
- Iron Creek Tunnel. Middle tunnel, aligned with the memorial from the southern approach.
- Scovel Johnson Tunnel. Southernmost, aligned with the memorial.
- Pigtail bridges. Three wood-truss spirals that wrap the road over itself. The northern pigtail above Doane Robinson Tunnel is the most photographed.
- Mount Rushmore overlook turnouts. Several pullouts along the route line up the memorial face through gaps in the trees.
- Norbeck Overlook. Wide pullout on the southern approach with interpretive panels about Peter Norbeck's design intent.
Where to Camp
Custer State Park has a dozen campgrounds; the closest to Iron Mountain Road are Game Lodge, Stockade Lake, and Center Lake. Black Hills NF dispersed camping is permitted off the road system on national forest land. Mount Rushmore National Memorial does not permit overnight stays; the closest commercial camping is in Keystone.
Tips for a Safe and Enjoyable Trip
- The Iron Mountain segment is not plowed. Closures from late November through March are routine.
- Vehicle clearance: 12 feet 4 inches max. Width: 8 feet max. Most RVs cannot fit.
- Use pullouts before tunnels to wait for oncoming traffic. Tunnels are one-lane.
- The road is slow by design. Allow at least an hour for the 17 miles.
- Custer State Park requires an entrance fee for the rest of the park. Iron Mountain Road itself is fee-free if you don't stop on the southern half within park boundaries.
- Combine with the Wildlife Loop Road and Needles Highway for a full day in Custer State Park.
