Cajon Pass — I-15 Summit and San Andreas Fault Viewpoint

Cajon Pass at roughly 4,260 feet is the gap between the San Gabriel and San Bernardino Mountains that funnels I-15, the BNSF railroad, and California Highway 138 through the same narrow slot carved by the San Andreas Fault. The geology here is raw and obvious — offset ridgelines, jumbled terrain, and the distinctive yellow-brown Cajon Formation exposed on the canyon walls. For overlanders heading from the Inland Empire toward Lone Pine Canyon and the San Gabriels, this is your last big fuel and resupply node before the terrain tightens up.

The Summit Inn area (or the Pilot/Flying J just off the pass) handles fuel, food, and last-resort supplies. This is also where Santa Ana winds funnel through hard — if conditions are red flag, fire behavior in the adjacent canyons can turn fast. Note it and plan accordingly before heading up-canyon.

San Andreas Fault gap — fuel up here.