Sierra Highway or El Camino Sierra is a road in Southern California, United States. El Camino Sierra refers to the full length of a trail formed in the 19th century, rebuilt as highways in the early 20th century, that ran from Los Angeles to Lake Tahoe following parts of modern State Route 14, U.S. Route 395 and State Route 89. Two portions of this road are currently signed as Sierra Highway. The first is an old alignment of SR 14/U.S. Route 6 from Los Angeles to Mojave. This road is also signed with the unusual designation of State Route 14U through the city of Santa Clarita. The second part signed as Sierra Highway is a portion of US 395 in Bishop.

State Route 14 (SR 14) is a north–south state highway in the U.S. state of California that connects Los Angeles to the northern Mojave Desert. The southern portion of the highway is signed as the Antelope Valley Freeway. Its southern terminus is at Interstate 5 in the Los Angeles neighborhoods of Granada Hills and Sylmar just immediately to the south of the border of the city of Santa Clarita. SR 14's northern terminus is at U.S. Route 395 (US 395) near Inyokern. Legislatively, the route extends south of I-5 to SR 1 in the Pacific Palisades area of Los Angeles; however, the portion south of the junction with I-5 has not been constructed. The southern part of the constructed route is a busy commuter freeway serving and connecting the cities of Santa Clarita, Palmdale, and Lancaster to the rest of the Greater Los Angeles area. The northern portion, from Vincent to US 395, is legislatively named the Aerospace Highway, as the highway serves Edwards Air Force Base, once one of the primary landing strips for NASA's Space Shuttle, as well as the Naval Air Weapons Station China Lake that supports military aerospace research, development and testing. This section is rural, following the line between the hot Mojave desert and the forming Sierra Nevada mountain range. Most of SR 14 is loosely paralleled by a rail line originally built by the Southern Pacific Railroad, and was once the primary rail link between Los Angeles and Northern California. While no longer a primary rail line, the southern half of this line is now used for the Antelope Valley Line of the Metrolink commuter rail system.