It travels to the northeast over Fremont Pass, passing the ghost town of Climax, home of the recently reopened Climax mine.

SH 91 ends at an interchange with I-70 at Wheeler Junction.

Since the development of the Copper Mountain Ski Resort area, Wheeler Junction is more commonly referred to as Copper Mountain.

As constructed in the 1920s, State Highway 91 went from Leadville, via Climax, Fremont Pass, Frisco, and Loveland Pass, to Empire, where it joined US 40.

In 1938, route 91 became US 6, until US 6 was rerouted over Vail Pass in 1941, leaving the portion of route 91 from Copper Mountain (formerly Wheeler Junction) to Leadville as the surviving part of this historic highway.