Cajon Pass

The San Andreas fault, where the North American and Pacific continental plates meet and grind together, a mountain range was formed millions of years ago. The single range divided and was cut at a right angle by streams flowing toward the lower basin, the higher plate tore away from the ridges. To the east, the San Bernardino range, to the west, the San Gabriels. This breach in the mountains became the "Cajon Pass." In Spanish, "Cajon", translates to "Box", which they felt the pass was shaped like.

The Cajon Pass was lived in and around by the Serrano Indians, although the Indians of the desert would travel through on nearby trails to trade with the coastal indians.

Spanish soldier, Pedro Fages, first traveled through the pass in his search for deserters from the Spanish Army. Horse thieves such as Walkara, known as the "Greatest horsethief in history", used the pass to escape with his thousands of horses stolen in raids. Later, Mormon pioneers, and those eager to find gold in the rush up north.

Cajon Pass as viewed looking south from the north ridge

Cajon Pass as viewed looking south from the north ridge

Looking south down the Cajon Pass

Trails were worn and established, and several smaller passes were used to enter the valley. Eventually, a toll road was cut and graded. A railroad was built; the toll road was paved, realigned and became the Old National Trails highway. Later on, the highway was upgraded again and became Route 66.

Ecology

Southern California Mountains and Valleys: San Gorgonio Mountains
This subsection comprises the lower and warmer parts of the San Bernardino Mountains, which are between the southern branch of the San Andreas fault on the south-southwest and the Mojave Desert on the north. ...

Southern California Mountains and Valleys: San Gabriel Mountains
This subsection comprises the lower and warmer parts of the San Gabriel Mountains, which are between the San Andreas fault on the north-northeast and the Los Angeles and Fontana Plains on the south. ...

Mojave Desert: High Desert Plains and Hills
This subsection consists of the western Mojave Desert, which is mostly alluvial plain and pediment, with relatively small areas of hills and low mountains. ...