Iron Mountain Road Guide (US-16A)
Iron Mountain Road is engineering as art. Seventeen miles of US-16A connect Mount Rushmore to Custer State Park through three pigtail bridges and three tunnels — and each tunnel is deliberately aligned so Mount Rushmore appears framed in the exit. It's the moment every Black Hills photographer chases and every rider who's done it remembers.
Drive the road south to north — from Custer State Park toward Mount Rushmore — so the framed views through the tunnels face you as you exit. The three pigtail bridges are wooden loops that twist back on themselves to gain elevation while preserving the landscape. They're a rare sight on a modern American highway and they ride beautifully on two wheels.
Combine Iron Mountain Road with Needles Highway for the full Black Hills scenic loop. Fuel up before you leave Sturgis — gas stations are sparse inside the loop.
RV Tunnel Restrictions
The smallest Iron Mountain tunnel (Scovel Johnson) is 10'7" wide and 12'2" high. Most class A motorhomes, fifth wheels and large trailers cannot pass safely. Leave the rig at Rush No More and drive a car or ride in.
Iron Mountain Road FAQ
How long is Iron Mountain Road?+
Iron Mountain Road (US-16A) is 17 miles between Mount Rushmore and Custer State Park. Allow 1 to 1.5 hours with photo stops at the tunnels and pigtail bridges.
What are the pigtail bridges?+
Three looping wooden "pigtail" bridges that twist back over themselves to gain elevation without cutting a straight scar into the mountain. Engineering designed intentionally to preserve scenery.
Can large RVs drive Iron Mountain Road?+
Three tunnels along US-16A are narrow. The smallest (Scovel Johnson Tunnel) is 10'7" wide and 12'2" high. Most motorhomes and large trailers cannot pass safely. Leave the rig at camp.
Why is the drive famous?+
Each of the three tunnels is aligned so that Mount Rushmore appears framed through the opening as you exit. It's the signature Black Hills driving moment.
Should I drive it in the direction of Rushmore or away from it?+
Drive from Custer State Park toward Mount Rushmore (south to north) so the framed views through the tunnels face you. That's the payoff direction.