In the Mountain Springs pass between San Diego and Imperial counties, the eastbound lanes traverse the pass on the former roadbed of US 80 through In-Ko-Pah Gorge near Myers Creek. The westbound lanes were placed on a different routing through Devil's Canyon that had been constructed by November 1963. A contract for paving the from the San Diego–Imperial county line to SR 98, including the eastbound lanes, was given to the Isbell Construction Company for $3.69 million (about $ in dollars) in May 1963. This portion was completed in May 1965 "through some of the most rugged, hottest sections of San Diego and Imperial counties," according to "The San Diego Union". Construction ran into difficulties following concerns regarding potential landslides. The westbound lanes were built first, and temporarily contained both directions of traffic while the old highway was converted into the eastbound lanes. The "Los Angeles Times" described the stretch east of Mountain Springs as follows: "Through it the freeway engineers have hacked two separate roadways not even in sight of each other, but so overpowering in the sheer magnitude of the cuts through the mountains that it is almost impossible to believe human beings could have so overpowered hostile nature ..." Access to the site for construction workers was difficult, and many slopes had to be stabilized. Temperatures reached in the summer and in winter, with winds reaching up to . While using nuclear explosions to conduct blasting operations in the Laguna Mountains was considered as a possibility, the proposal was not considered to be practical at the time. Two cables and a hook were used to move girders into place; this was the first use of a cable in Southern California road construction.