U.S. Route 16A

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U.S. Highway 16A
US 16A highlighted in red
Route information
Auxiliary route of US 16
Maintained by SDDOT
Length	36.971 mi[1] (59.499 km)
Major junctions
West end	US 16 / US 385 / SD 89 in Custer
East end	US 16 near Keystone
Location
Country	United States
State	South Dakota
Counties	Custer, Pennington
Highway system
United States Numbered Highway System List Special Divided South Dakota State Trunk Highway System Interstate US State
← US 16 → SD 17

U.S. Highway 16A (US 16A) is a 36.971-mile (59.499 km) scenic United States Numbered Highway. It is an alternate route for US 16. It splits from US 16 in the Black Hills of the southwestern part of the U.S. state of South Dakota. The highway's western terminus is an intersection with US 16, US 385, and South Dakota Highway 89 (SD 89) in Custer. The eastern terminus is at an interchange with US 16 called Keystone Wye south of Rapid City. Portions of US 16A are known as the Iron Mountain Road, named after the peak it summits.