Granite Spires Along Needles Highway, Custer State Park

Custer State Park's granite formations here are part of the Harney Peak granite, an igneous intrusion roughly 1.7 billion years old that has weathered into the tall, cracked spires and pinnacles known as the Needles. The Needles Highway, a 14-mile route completed in 1922 under the direction of South Dakota governor Peter Norbeck, winds through this section of the park to showcase the rock formations up close. Norbeck reportedly walked and mapped the road's course himself before construction, insisting the route bend around the granite rather than blast through it. The park itself, established in 1919, covers more than 71,000 acres and was named for Lieutenant Colonel George Armstrong Custer, who led an 1874 expedition into the Black Hills.