Slide showing the road on the summit of Mosquito Pass. Mosquito Pass, 13,187 feet in elevation, was at about twenty-one miles the shortest route to Leadville from the mining camps of Park County. The Pass was heavily traveled with the new strikes in Lake County in 1878, but was a dangerous route during the winter months. A toll road was constructed by the Mosquito Pass Wagon Road Company by 1879. Construction of a rail line in 1882 replaced most of the traffic over the Pass.