SR 118 used to extend past I-210 on
Foothill Boulevard through
Sunland-Tujunga,
La Crescenta and
La Cañada, then across the
Arroyo Seco into
Pasadena, where SR 118 ran on Lincoln Avenue and Fair Oaks Avenue, ending at
Colorado Boulevard (
US 66 Alternate). The original routing across the Arroyo Seco ran along La Cañada Verdugo Road (now Oak Grove Drive), which crossed the arroyo along the crest of Devil's Gate Dam. In 1957, the first segment of the
Foothill Freeway was completed between Montana and Cañada Streets in Pasadena and Foothill Blvd and Michigan Avenue in La Cañada. SR 118 ran along this short freeway until 1974, when the current Foothill Freeway alignment over the Arroyo Seco was completed further to the south. SR 118 was then truncated to its current terminus with I-210 near San Fernando. Before the freeway was built, the route went through Simi Valley on Los Angeles Avenue and Kuehner Drive, then crossed into the San Fernando Valley on Santa Susana Pass Road. The eastern segment used Devonshire Street through the San Fernando Valley, then cut through San Fernando along Brand and Maclay Streets before joining Foothill Boulevard in Sylmar. During the
1932 Summer Olympics, it hosted part of the
road cycling event. The SR 118 freeway began construction in 1968 and the last section of freeway opened in 1979. The segment of freeway between Balboa Boulevard and Tampa Avenue was one of the last freeway segments to be built in the Los Angeles area. As a result of the
Northridge earthquake in January 1994, a section of the highway between I-405 and I-210 was closed for over one month while damage to an overpass was repaired. The Porter Ranch Drive interchange is relatively new; before it was constructed, that interchange connected to a closed Winnetka Avenue and a
Park and Ride lot. Route 118 from Route 23 to Route 210 was named the
Simi Valley-San Fernando Valley Freeway by Assembly Concurrent Resolution 145, Chapter 185 in 1970. The name was reintroduced by State Senators
Lockyer, Maddy, and Wright as State Senate Resolution 7, amended and enrolled December 5, 1994. Since it was neither a concurrent resolution nor a joint resolution, it was not filed with the Secretary of State. The rationale for choosing this name for State Route 118 is that the western end of the highway, at the time the bill was passed, is very close to the
Ronald Reagan Presidential Library. There is an additional unconstructed segment of SR 118, defined in 1959 in the
California Streets and Highways Code, extending from its current terminus with I-210 to a planned
SR 249, located within the
Angeles National Forest. This appears to have been roughly planned to run primarily along Big Tujunga Canyon between Foothill Boulevard and
Los Angeles County Route N3,
Angeles Forest Highway, which is the current traversable routing for unconstructed SR 249. ==Major intersections==