Early planning

I-105 was an integral part of a Caltrans 1960s master plan for the Southern California freeway system, but did not open until 1993. The right-of-way was included on several early highway plans since at least 1947, although it was not named the "Century Freeway" until 1956, and was numbered Route 42. In 1965, the Century Freeway was added to the state system originated at State Route 1 (Sepulveda Boulevard) east to Central Avenue in the City of Los Angeles along an alignment very near to the current right-of-way.^[10] The current route was added to the Interstate system in 1968.

Design and local opposition

The route was designed between 1968 and 1972 by Caltrans District 7, under the direction of Design Chief Sid Elicks.^[6] However, opposition from some of the communities through which the right-of-way would pass slowed the process and led to some reroutings. Many factors contributed to the delay. The growth of the environmental movement in the 1960s created resistance to new freeway construction. Fiscal difficulties brought about by the 1971 Sylmar earthquake and the California tax revolt of the late 1970s further hampered Caltrans' construction efforts.^[11]

However, the major source of resistance to the freeway's construction was community opposition and the side effects of these demands. By the early 1970s, most of the areas in the freeway's path (and thus slated to be demolished) were predominantly African-American. Resentment over previous freeway projects' effects on other black communities resulted in significant modifications to the original route. Most cities along the way, weary of the noise and visual blight created by elevated freeways, demanded that the route be built far below grade in a "trench". Also, another source for resistance to the freeway's construction was that much of the I-105 path was going to be built in low income, high crime neighborhoods, which also delayed the freeway's construction until the crime in the areas went down.

Norwalk was opposed to the freeway's proposed route through its city center, and blocked the freeway from reaching its intended terminus at the Santa Ana Freeway (I-5); however, Caltrans had already decided to abandon that section due to the inability of the severely congested Santa Ana Freeway to accommodate any more traffic.

Keith v. Volpe

In 1972, community opposition resulted in a federal lawsuit, Keith v. Volpe, being filed, charging a violation of various civil rights protections and the National Environmental Policy Act (NEPA). An important figure in the freeway's history was Harry Pregerson, a United States federal judge who presided over the lawsuit concerning the freeway's construction and chose to continue presiding over the case despite being promoted to a higher level court.^[12] The interchange with I-110 is named the Judge Harry Pregerson Interchange in his honor.^[13] In 1972, Judge Pregerson enjoined the further development of the freeway until it has complied with the requirements of NEPA, the California Environmental Quality Act (CEQA), the Federal-Aid Highway Act, and the Uniform Relocation Assistance and Real Property Acquisition Act of 1970.

In 1979, this lawsuit resulted in a Consent Decree, amended in 1981, which imposed several conditions on the development of the freeway, including additional public hearings, preparation of an environmental report, alterations to the design to reduce lanes and intersections, improve carpooling and provide for a transitway, which became the Los Angeles Metro Rail Green Line, now known as the C Line. A portion of the right-of-way was also to be constructed below grade to buffer adjacent areas from the effects of traffic noise. After construction began in the 1980s, failure to perform a complete survey of the area's groundwater deposits, combined with the 20–30-foot (6.1–9.1 m) below-grade trench through the city of Downey, resulted in buckling and cracking along the eastern portions of the route. At one point, a giant sinkhole opened in the Bellflower Boulevard on-ramp. This resulted in the construction of an elaborate pump system along the freeway between the interchanges with I-710 and I-605.

Century Freeway Housing Program

A significant aspect of the Keith v. Volpe Consent Decree was the requirement that the housing removed to construct the freeway be replaced, leading to the creation of the Century Freeway Housing Program within the California Department of Housing and Community Development.

Post-construction

Westbound view along I-105 heading towards Vermont Ave, through the I-110 interchange

Throughout the difficulties, Congressman Glenn M. Anderson (D-San Pedro) tirelessly advocated for the route's construction, making claims it would provide congestion relief along Century, Manchester, and Firestone Boulevards and the Imperial Highway, as well as relieving pressure on the Santa Monica (I-10) and San Diego (I-405) Freeways for travelers between Downtown Los Angeles and LAX. After Anderson's death in 1994, Caltrans honored him by renaming the freeway in his honor. However, the route's original name, "Century Freeway", is still used on a number of maps.^[14]

The freeway was originally signed with El Segundo as its westbound control city; however, in recent years, many of the El Segundo signs have been replaced and/or covered with "LAX Airport" signage due to the western terminus' proximity to Los Angeles International Airport.

Shortly before opening, filmmakers had access to use the empty freeway for a number of weeks to film the 1994 motion picture Speed.

Interstate 105 (1964–68)

Previously, the I-105 designation was used for U.S. Route 101 (the Santa Ana Freeway, US 101) from I-5 (the Golden State Freeway) at the East Los Angeles Interchange to the connection to I-10 (the San Bernardino Freeway; this connection had been I-110); it went back to US 101 in 1968.^[15]