California State Route 178

State Route 178 (SR 178) is a state highway in the U.S. state of California that exists in separate constructed segments. The western segment runs from State Route 99 in Bakersfield and over the Walker Pass in the Sierra Nevada to the turnoff for the Trona Pinnacles National Natural Landmark. Though some maps and signs mark this segment of SR 178 as continuous through Downtown Bakersfield, control of the portion between the Kern River Bridge and M Street was relinquished to the city and is thus no longer officially part of the state highway system. The eastern segment of SR 178 runs from the southeasterly part of Death Valley National Park to Nevada State Route 372 at the Nevada state line west of Pahrump. The gap between Trona Pinnacles and the southeasterly part of Death Valley is connected by various local roads and State Route 190 through the park.

SR 178 serves many different purposes. It connects Downtown Bakersfield with East Bakersfield and Lake Isabella. It is one of three crossings over the Sierra Nevada south of Yosemite (SR 120, Tioga Pass Road), connecting the southern San Joaquin Valley with the upper Mojave Desert and the Owens Valley. This also provides access to Death Valley National Park. If the unconstructed portion through Death Valley was built, it would provide a continuous route between Bakersfield and the Las Vegas Valley via Pahrump.