Interstate 10 in California - History

History

What is now Interstate 10 east of Los Angeles was generally part of the Atlantic and Pacific Highway, one of many transcontinental national auto trails. By 1926, when the United States Numbered Highways were assigned, the road across the desert east of Indio was unimproved, while the road from Indio west to San Bernardino (as well as various roads west to Los Angeles) was paved. In late 1926, U.S. Route 99 was designated along the section of road from San Bernardino to Indio, where it turned south along present State Route 86 on the west side of the Salton Sea. West of San Bernardino, US 99 ran to Los Angeles concurrent with U.S. Route 66 (via Pasadena) before turning north; this route to Los Angeles is north of the later alignment of Interstate 10. The piece of this between San Bernardino and Indio was defined in 1915 as Legislative Route 26. (It continued south from Indio via El Centro to Heber; see U.S. Route 99 and State Route 86 for details. A 1931 extension took it south to Calexico on present State Route 111.)

The route from Indio via Mecca to the Arizona state line near Blythe was defined in 1919 as pre-1964 Legislative Route 64. (Later extensions took LR 64 west along present State Route 74; a 1931 cutoff bypassed Mecca to the north.) LR 26 was extended west from San Bernardino to Los Angeles in 1931, running along an alignment south of the existing US 66/US 99. Neither of these was a signed route until ca. 1932, when U.S. Route 60 was extended west from Arizona to Los Angeles, running along LR 64 to Indio, LR 26 (with US 99) to Beaumont, pre-1964 Legislative Route 19 to Pomona, and LR 26 to Los Angeles. (The original alignment of LR 26 ran roughly where State Route 60 now is west of Pomona, but an alignment close to present I-10 opened ca. 1934).

Thus, in 1931, what is now I-10 east of Los Angeles had been defined as LR 26 from Los Angeles to Indio and LR 64 from Indio to Arizona. It was signed as US 99 from San Bernardino to Indio, and US 60 came along ca. 1932 from Los Angeles to Pomona and from Beaumont to Arizona. U.S. Route 70 was extended west from Arizona ca. 1936 along the whole route to Los Angeles, and, between 1933 and 1942, US 99 moved from US 66 to present I-10 between San Bernardino and Los Angeles, forming a three-way concurrency between Pomona and Los Angeles. Old alignments and names include Valley Boulevard, Ramona Boulevard and Garvey Avenue.

The route east from Los Angeles was added to the Interstate Highway System on August 7, 1947. It was assigned the I-10 number on August 14, 1957, and the short piece west of I-5 was approved as I-110 on November 10, 1958. By then, most if not all of the San Bernardino Freeway had been completed, and I-10 was signed along the existing freeway along with US 70, US 99, and part of US 60. Those three routes were all removed in the 1964 renumbering, leaving only I-10.

The part west of downtown Los Angeles was pre-1964 Legislative Route 173, defined in 1933 from Santa Monica to downtown Los Angeles. It was signed as State Route 26 by 1942, running along Olympic Boulevard. It was later replaced by the Santa Monica Freeway, and added to the Interstate Highway System on September 15, 1955. It too was assigned the I-10 number on August 14, 1957. It was completed ca. 1964, and became Route 10 in the 1964 renumbering.

Portions of the Santa Monica Freeway going over La Cienega Boulevard collapsed after the Northridge earthquake on January 17, 1994, and were rebuilt using new Seismic-Resistant bridge designs.