U.S. Route 16A

US 385 / SD 89 in Custer
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;

U.S. Highway 16A (US 16A) is a 36.971-mile-long (59.499 km) scenic

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

.

Route description

The route passes through

Mount Rushmore National Memorial, the Norbeck Wildlife Management Area and Black Elk Wilderness within Black Hills National Forest, and Custer State Park (including State Game Lodge and Legion Lake

), before rejoining the parent highway.

US 16A is famous for its scenic, one-lane tunnels aligned to frame the faces on Mount Rushmore, its "

pigtail bridges

", and its sections of divided highway but with single (and narrow) lanes on each roadway. It is the only route which can be used to drive through Custer State Park without having to pay an entrance fee for the park, provided the traveler does not stop in the park.

The route includes most of the tunnels on the South Dakota state highway system, including the only three-lane tunnel in the state, just north of Keystone. Part of the highway is also a boundary of the Black Elk Wilderness. The Iron Mountain portion of the road is not maintained in the winter. The road, like several other scenic roads in the Black Hills, was originally laid out by Governor Peter Norbeck, specifically to create a very scenic, slow-speed road for tourists. The section of US 16A from SD 89 to SD 244 is known as the Peter Norbeck Memorial Byway in honor of the governor. At the highest point of the byway, on the summit of Iron Mountain, there is a small memorial to Governor Norbeck.

History

An older road through the

US 16A

between 1944 and 1980.

Major intersections

County	Location	mi^[1]	km	Destinations	Notes
US 385 / SD 89 south	Western terminus; western end of SD 89 concurrency
	0.804	1.294	SD 89 north	Eastern end of SD 89 concurrency
	Custer State Park	6.447	10.375	SD 87 south	Western end of SD 87 concurrency
		7.875	12.674	SD 87 north	Eastern end of SD 87 concurrency
		16.226	26.113	SD 36 east	Western terminus of SD 36
Pennington	Mount Rushmore	33.221	53.464	SD 244 west	Eastern terminus of SD 244
	Keystone	34.321	55.234	SD 40 east	Western terminus of SD 40
	directional-T interchange
1.000 mi = 1.609 km; 1.000 km = 0.621 mi Concurrency terminus