The Hollywood Freeway is one of the principal freeways of Los Angeles, California (the boundaries of which it does not leave) and one of the busiest in the United States. It is the principal route through the Cahuenga Pass, the primary shortcut between the Los Angeles Basin and the San Fernando Valley. It is considered one of the most important freeways in the history of Los Angeles and instrumental in the development of the San Fernando Valley. It is the second oldest freeway in Los Angeles (after the Arroyo Seco Parkway).
<blockquote>Route 170 is from Route 101 near Riverside Drive to Route 5 near Tujunga Wash.</blockquote>
In addition to the above, the original 1963 definition of Route 170 included "Route 405 near Inglewood to Route 101 in Los Angeles" in a separate subdivision. This was defined in anticipation of the Laurel Canyon Freeway, which never came to fruition. In 1970, the definition was amended to subdivide the portion south of US 101 as "(a) Los Angeles International Airport to Route 90." and "(b) Route 2 to Route 101 in Los Angeles," deleting the segment between SR 2 and an extension of SR 90 that was never constructed. Subdivision (b) would run along Highland Avenue in Hollywood. In 2015, the state relinquished Highland Avenue to the city of Los Angeles, and the legislature amended the definition to reflect that as well as remove the final unconstructed freeway segment. However, subdivision (b) was also modified to require the city to still "maintain signs directing motorists to the continuation of Route 170". and are part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration.
As of 2018, Caltrans is planning to add soundwalls to SR 170 in both directions between Sherman Way and the Hollywood Split. There are currently some neighborhoods located near the freeway, which cause noise pollution. Now that soundwalls are in place, it can reduce the noise and reduces smog.
History
Plans for the Hollywood Freeway officially began in 1924 when Los Angeles voters approved a "stop-free express highway" between Downtown Los Angeles and the San Fernando Valley.
The Hollywood Freeway is an expansion of the original Cahuenga Parkway, a short six-lane freeway that ran through the Cahuenga Pass between Hollywood and Studio City. The Cahuenga Parkway featured Pacific Electric Railway "Red Car" tracks in its median, but by the 1950s these tracks were out of service due to radical reductions in Red Car service. The Pacific Electric right-of-way later accommodated an additional lane in each direction.
The second location of Los Angeles High School was in the path of the freeway. The school moved to its third and current location in 1917. The school buildings were converted into a school for habitually truant boys until 1948, when it was demolished to make way for the freeway.
SR 170 was originally supposed to run from the I-5 interchange to I-405 near the Los Angeles International Airport as the Laurel Canyon Freeway under the Laurel Canyon Boulevard, Crescent Heights Boulevard and La Cienega Boulevard alignments of today. In fact, much of La Cienega Boulevard between Manchester Avenue and Venice Boulevard was constructed to freeway standards, with several grade-separated interchanges, although it is now an expressway maintained by Los Angeles County.
California's legislature has relinquished state control of the segment of SR 170 along Highland Avenue, and thus that portion is now maintained by the City of Los Angeles. Despite the relinquishment, exit numbers assigned at SR 170 remain starting at 5A at the Hollywood Split instead of 1 or 0.