Despite being one of the highest mountain passes in the state, the only steep part is the switchback on the final ascent toward the Climax mine on the south side.

The Denver, South Park and Pacific Railroad built a narrow gauge railway over Fremont Pass in 1884.

It was sold in foreclosure proceedings to the Denver, Leadville & Gunnison Railroad in 1889 and became later part of the Colorado and Southern Railway.

The line south of Climax is retained, converted to 4 ft 8+1⁄2 in (1,435 mm) standard gauge in 1943 and now operated by Leadville, Colorado and Southern Railroad.

[4] In 1909, the Shoshone Transmission Line was built to connect a generating station near Glenwood Springs with Leadville and Denver.