As Interstate 8 was built across San Diego County’s rugged mountains in the 1960s and 1970s, the most difficult section was creating the two, crisscrossing traffic lanes up and down Mountain Springs Grade, which jumps back-and-forth across the San Diego-Imperial county line east of Jacumba.
This engineering and construction challenge — and its history — are documented in the January-February 1964 edition of California Highways and Public Works, a copy that’s preserved and available at archive.org.
The story goes back to the days before the Civil War, when the route was described as a place where “Only the courageous or the desperate attempt to cross the mountains between San Diego and the Colorado River.”
When the story was published, only part of the new highway—still in use today—was open; it expanded on work done in 1938.
“The principal portion of the project follows Devil’s Canyon, a mile and a half north of the present Highway 80,” wrote Don W. Gray, Resident Engineer. “The alignment selected fell largely on steep boulder-strewn and faulted hillsides rising from the canyon floor at a 1:1 slope or greater. For the coming year the newly constructed 36-foot paved section will carry two-way traffic while work is proceeding on the realignment of existing Highway 80 in Myer Canyon.”
Want to visit? Take my Towering Old Highway drive in Joyrides Around San Diego or the Amazon Kindle chapter. From the Desert View Tower, you can see most of today’s Interstate 8, plus the other road cuts that once carried traffic up-and-down from the mountains to the desert.