Part 1; the history of Tehachapi-Willow Springs Road
Oak Creek Pass and Willow Springs were known to the local tribes of the Tehachapi Mountains for generations. The first documented European crossing of Oak Creek Pass was during 1776 as part of an expedition by Francisco Garces. Oak Creek Pass is as used again by John C. Fremont during an 1844-1845 expedition to explore San Joaquin Valley. Both the parties of Garces and Fremont stopped at the site of Willows Springs which at the time was known to be a reliable source of water.
The reliability of Willow Springs was later reaffirmed by the Jayhawk Party. The Jayhawk Party had stopped at Willows Springs on the way to Los Angeles after struggling to escape Death Valley.
The importance of the reliable water source at Willow Springs would see it become part of the early Stockton-Los Angeles Road. The emergence of the Kern River Gold Rush in the southern Sierra Nevada Mountains during 1853 spurred interest in the creation of an organized wagon road which connected Stockton to Los Angeles. The quickest known routing from the Kern River in southern San Joaquin Valley towards Antelope Valley during the early 1850s was over the Tehachapi Mountains via Tejon Pass (now Old Tejon Pass). Tejon Pass crossed the Tehachapi Mountains at an elevation of 5,285 feet above sea level and passed by the site of Willow Springs upon emerging into Antelope Valley. From Willow Springs the routing of the Stockton-Los Angeles Road south to Elizabeth Lake and San Francisquito Canyon was largely direct.
In 1853 Castac Pass through Grapevine Canyon west of the Old Tejon Pass was surveyed by Robert S. Williamson of the Army Corps of Engineers for a possible path of Transcontinental Railroad. The 1853 surveying expedition found Castac Pass through Grapevine Canyon to be a far more viable route for travelers and the primary alignment was of the Stockton-Los Angeles Road was shifted west from Old Tejon Pass. Castac Pass had a far lower terminal elevation at 4,144 feet above sea level and had a gentler grade through Grapevine Canyon. In 1854 a U.S. Army Garrison was established at Fort Tejon in Grapevine Canyon near modern Lebec to protect settlers and travelers along the Stockton-Los Angeles Road. In time Castac Pass became known as Fort Tejon Pass and eventually simply Tejon Pass. Tejon Pass would later become part of the Ridge Route (US Route 99) alignment and Interstate 5.