U.S. Route 16A The route passes through Keystone, South Dakota; Mount Rushmore National Memorial; The Norbeck Wildlife Management Area and Black Elk Wilderness within the 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
Mount Rushmore average per year, enough to support abundant animal and plant life. Trees and other plants help to control surface runoff. Dikes, seeps, and springs help to dam up water that is flowing downhill, providing watering spots for animals. In addition, stones like sandstone and limestone help to hold groundwater, creating aquifers. A study of the fire scars present in tree ring samples indicates that forest fires occur in the ponderosa forests surrounding Mount Rushmore around every 27 years. Large fires are not common. Most events have been ground fires that serve to clear forest debris. The area is a climax