Cajon Pass

A map of the Cajon Pass area, showing the Old Spanish Trail, Interstate 15, Highway 138, and the PCT
The Old Spanish Trail is shown as it traverses Horsethief Canyon and then runs parallel to I-15.

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Quick Facts
At the head of Horsethief Canyon, near Interstate-15 and the Cajon Summit corridor.
Cajon Pass is a mountain pass between the San Gabriel and San Bernardino Mountains and the route of the Old Spanish Trail.
National Forest; Pacific Crest National Scenic Trail

Cajon Pass is a mountain pass between the San Gabriel and San Bernardino Mountains and the route of the Old Spanish Trail. This important box canyon has been used by thousands of years as a passage from the Mojave Desert to the Los Angeles Basin. It is currently grouped with Cajon Summit to describe the area where a vital artery of the California interstate system, Interstate 15, descends into Los Angeles, after traveling east from Las Vegas. The Interstate 15 corridor through this area also serves as a part of the mother road, Route 66. 

During the Old Spanish Trail days, travelers who were exhausted after navigating Cajon Pass would luckily stumble upon the homestead of Isaac Slover and his wife, María Bárbara Aragón Slover, who regularly assisted travelers on the Old Spanish Trail. Isaac opened his smokehouse and supplied the famished travelers with bacon and squashes, a feat of generosity that seems to have been a regular occurrence. New settlers found that the Slovers would help them survive until their own crops had been planted and harvested. 

The Mexican government was beginning to grow weary of outsiders, but Slover's eventual marriage to María Bárbara Aragón, his conversion to Catholicism, and his acceptance of Mexican citizenship provided him with the means to trap and trade freely along the Old Spanish Trail. They relocated to California's San Bernardino Valley in 1837, and--along with other New Mexican emigrants--founded the communities of Agua Mansa and La Placita de los Trujillos in the 1840s. 

Pacific Crest Trail

The Pacific Crest Trail (PCT) traverses through Cajon Pass, with a section that parallels the Old Spanish Trail. This is a great opportunity to hike a portion of the trail, but should only be attempted by experienced hikers. Access is via Elliot Ranch OHV Road 3N22. Please contact the San Bernardino National Forest for more information.

Site Information

Location (Cajon Pass is at the head of Horsethief Canyon, traversed by California State Route 138 (SR 138) and railroad tracks owned by BNSF Railway and Union Pacific Railroad. The Cajon Summit corridor, which includes Interstate 15, is near Cajon Pass, and the trail passes under the Interstate, and west of the Interstate into the Los Angeles basin.)

Safety Considerations

More Site Information

Old Spanish National Historic Trail

Old Spanish National Historic Trail

Last updated: November 29, 2023