Historically, Henness Pass Road was a travel route used by Native Americans and then immigrants and local mining communities during the Gold Rush era.

[2] From there it was carried by wagons, with part of the route being via the Bridgeport Covered Bridge and the Virginia Turnpike,[3] which connected to the road to Henness Pass at North San Juan.

[5] Charles Marsh was a founding director of the Henness Pass Turnpike Company, and was a civil engineer who built and owned water systems serving the mines and towns of Nevada County, California beginning in the 1850s.

His intimate familiarity with the topography of the area led to his accompanying Theodore D. Judah (who wanted to build a transcontinental railroad) on a reconnaissance of the Sierra Nevada Mountains in 1860.

They proceeded over the Henness route, taking elevations and measurements, and came back both convinced that a railroad crossing of the imposing mountains was feasible.