Its southern terminus is at Interstate 5 (I-5, Golden State Freeway) in the Los Angeles neighborhoods of Granada Hills and Sylmar[2] just immediately to the south of the border of the city of Santa Clarita.

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 (south of Palmdale) 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.

Linked with US 395, this road also connects Los Angeles with such places as Mammoth Mountain, Mono Lake, Yosemite National Park and Reno, Nevada.

The highway crests the Sierra Pelona Mountains via Escondido Summit, at an elevation of 3,258 feet (993 m), before descending and passing by Acton to the north.

[6] Between Pearblossom Highway and Avenue S, there is a vista point overlooking Lake Palmdale, which features a historic plaque that honors aviation accomplishments including the Space Shuttle, breaking the sound barrier and the speed record.

[11] The freeway portion terminates just south of Mojave, where SR 14 serves as the main street and runs through the downtown area.

To the east of the route is Mojave Air & Space Port, home to the National Test Pilot School and SpaceShipOne, the first privately funded human spaceflight,[12] as well as a vast airplane graveyard; all are visible from SR 14.

Now a divided highway with at-grade intersections, departs the corridor of the rail main, to follow the crest of the forming Sierra Nevada mountains.

The scenery also changes, as the highway departs the Mojave Desert and crosses Red Rock Canyon State Park.

As US 395 the route continues to follow the crest of the Sierra Nevada, serving Owens Valley, Mammoth Mountain, Yosemite National Park and Mono Lake.

The Los Angeles Times declared El Camino Sierra complete in 1931, when the portion from Mojave to the Owens Valley, along modern US 395, was paved.

The Cajon Pass fork remains the primary freight rail line to connect southern and northern California in use today, now owned and operated by the Union Pacific Railroad.

By 1925, the Midland Trail was established along what is modern State Route 168, joining El Camino Sierra in Big Pine.

[19] Parts of modern SR 14 continue to be signed with these names,[6] and north of Los Angeles County is still officially designated "El Camino Sierra / Midland Trail" as well as the aforementioned "Aerospace Highway".

[21] The Newhall Pass interchange, where I-5, Sierra Highway, Foothill Boulevard, San Fernando Road and the southern terminus of SR 14 meet, has been the site of a number of catastrophic incidents.

[26] The interchange with Sierra Highway at Via Princessa in Santa Clarita has an unusual design, with long flyover ramps for the connections.

In response, multiple government agencies have proposed adding more transportation arteries between Los Angeles and the Antelope Valley, as well as expanding the capacity of the existing SR 14 and rail corridors.

Preliminary studies estimated costs around $3 billion and suggested charging a varying toll, adjusted for the time of day, averaging around $8 for one-way passage.

[32] Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage.