Tehachapi Pass is a mountain pass crossing the Tehachapi Mountains in Kern County, California in the United States. Traditionally, the pass marks the northeast end of the Tehachapis and the south end of the Sierra Nevada range. The route is a principal connector between the San Joaquin Valley and the Mojave Desert. The Native American Kitanemuk people used the pass as a trade route before the American settlement of the region in the 1800s. The main line of the former Southern Pacific Railroad (now owned by the Union Pacific Railroad and shared with BNSF Railway) was constructed through the pass in the 1870s. This was eventually followed by U.S.