Interstate 405

Interstate 405. Known as the San Diego Freeway, it is a major north–south auxiliary Interstate Highway in the Southern California region. It runs approximately 72 miles from Irvine to Mission Hills, entirely within the Los Angeles metropolitan area, and is one of the busiest highways in the United States. The route serves as a vital bypass of downtown Los Angeles for Interstate 5, connecting key employment centers like the Westside and the South Bay.

Route description

The highway begins at a complex interchange with Interstate 5 in the City of Irvine, within Orange County. It proceeds northwest, passing through the University of California, Irvine campus and skirting the western edge of the Irvine Spectrum area. Entering Los Angeles County, it traverses the Conejo Valley before ascending the Santa Monica Mountains via the Sepulveda Pass. Through this pass, it provides a critical link between the San Fernando Valley and the Westside, passing near the Getty Center. South of the mountains, it runs through the heart of the Westside, paralleling the Pacific Ocean and serving LAX before turning inland. The freeway concludes at its northern terminus, another massive interchange with Interstate 5 in the Mission Hills district of the San Fernando Valley.

History

The route was originally conceived as part of the California Freeway and Expressway System plan in the 1950s, with construction beginning in the early 1960s. Key segments, including the challenging engineering feat through the Sepulveda Pass, were opened to traffic throughout the decade. It was formally designated as part of the Interstate Highway System and received its I-405 designation. The freeway gained national notoriety for its extreme congestion, famously depicted in films like *Falling Down* and serving as the setting for a legendary chase scene in the movie *La La Land*. Major modernization projects have been undertaken, including the massive Carmageddon closure in 2011 to demolish the Mulholland Drive bridge and the ongoing Sepulveda Pass improvements.

Junction list

The entire route is in the Los Angeles metropolitan area. Key junctions from south to north include the southern terminus at Interstate 5 in Irvine. It interchanges with State Route 73 in Irvine, State Route 133 near Laguna Beach, and State Route 22 in Orange County. In Los Angeles County, major interchanges occur with Interstate 605 near Downey, State Route 90 in Culver City, and Interstate 10 near Santa Monica. It meets U.S. Route 101 in the Sepulveda Pass and State Route 118 in the San Fernando Valley before reaching its northern terminus at Interstate 5 in Mission Hills.

Auxiliary routes

As a three-digit Interstate, it is itself an auxiliary route of its parent, Interstate 5. There are no signed auxiliary routes branching directly from it, but it connects to numerous other major highways that serve as crucial corridors in the regional network. These include the aforementioned Interstate 10, U.S. Route 101, and Interstate 605. The freeway also has direct connectors to several important state routes, such as State Route 2 near Santa Monica and State Route 107 in Lawndale.

See also

* Interstate 5 in California * Transportation in Los Angeles * List of Interstate Highways in California * Southern California freeways

Category:Interstate Highways in California Category:Transportation in Los Angeles County, California Category:Transportation in Orange County, California