Iron Mountain Road
US 16AKeystone to Custer State Park · South Dakota
Distance23.0mi · 37 km
Drive time48 minon the road
DifficultyModerate
MountainForest
Pigtail bridges and tunnels framing Mount Rushmore.
US 16A, Iron Mountain Road, climbs through the Black Hills on a deliberately playful route of corkscrew 'pigtail' bridges and narrow tunnels that frame Mount Rushmore in the distance. Mind the one-lane tunnels, the tight spirals, and the heavy summer traffic.
Where it runs
KeystoneStart · South Dakota
Custer State ParkEnd · United States
Character
Corners36bends
Tightness6of 10
Max gradient7%≈ 1-in-14
Hairpins9tight bends
Climb569 mtotal ascent
Summit1652 mhighest point · 5420 ft
SpringSummerAutumn
Elevation
485 m rangeKnow before you go
- One-lane tunnels
- Tight corkscrew bridges
- Heavy summer traffic
Sources
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