The approach on the eastern side is fairly gentle, ascending from near Grant up a gulch at the headwaters of the North Fork.

The western side of the pass has a steeper ascent, winding up the flank of a mountainside east of the town of Jefferson.

The increase in traffic led to the widening of the trail into a wagon road; during the Colorado Silver Boom the pass became one of the main routes of entry for eager immigrants to Leadville, Breckenridge, and Aspen.

[2] In 1879 the pass was traversed by the narrow gauge Denver, South Park and Pacific Railroad, and later the Colorado and Southern Railway, providing the first rail link between Denver and the South Park mining communities such as Fairplay (the tracks were removed in 1938, but the modern highway follows the old road and the railroad route over the pass - most of which is still visible).

During this same year of 1879, the poet Walt Whitman crossed the pass and described its summit with these words, later published in Specimen Days: On July 25, 1936, Denver and Rio Grande Western locomotive #346, which was on loan to the Colorado and Southern at the time, rolled on the east side of the pass as it hit a corner at an estimated speed of ~40 mph.