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Interstate Types and History
Interstate Highway Types and the History of California's Interstates

Interstates Turn 50: History of Interstates in California

WarningNote: The “Interstates Turn 50” series of pages were originally published on the Caltrans website in 2006. They disappeared from the site in June 2019. Knowing that of the goals of this site is to preserve information about the state highway system, and that includes information that was once on the Caltrans website but later disappeared, a friend from Caltrans requested that I explore saving these pages. Luckily, the pages in this series were preserved in the Internet Wayback Machine, and Caltrans has not asked the Internet Archive to take them down. This is because Caltrans is good about giving permission to use photos for nonprofit use. The images here used to be right there on Caltrans' publicly accessible site, and are posted elsewhere around on hobbyist sites. Still, if you wish to use an image, please formally request the image from Caltrans, and indicate you saw it…on the Internet Wayback Machine

History of Interstates in California

The list of California’s first sections of interstate is quite impressive. California already had more than half a dozen routes by 1947, totaling 1,938 miles, including I-5, I-8, I-10, I-15, US 40, I-80, I-505, and I-580. “Beltline and circumreferential” routes (more commonly called bypasses, such as today’s I-710, I-280, and I-880) were added in 1955 bringing California’s total interstate miles to 2,135. On June 24, 1957, I-80 became the first California freeway opened under the Federal Highway Act of 1956. I-10, one of the oldest interstates, was the first California interstate project to go to construction with interstate construction funds under the 1956 Act.

Construction of I-80, Alameda County
Construction of I-80, Alameda County, August 15, 1948. Construction of I-80, which began in 1947, connects San Francisco throught Sacramento over the Sierra and was the first California freeway opened under the Federal Highway Act.

The number of limited access highways already in existence in California before 1956, when the Federal-Aid Highway Act was signed, underscores California’s historic role as a leader and innovator in the construction of highway routes. Over 60 years earlier, on March 26, 1895, the state of California secured the title and right of way to the Lake Tahoe Wagon Road, which crossed the high Sierra into Nevada, and established a commissioner for this road. The Lake Tahoe Wagon Road, California’s first state highway, which officially became Highway 50 (US 50) in 1927, is also known as the “backbone of America” and is commemorated as such by the Highway 50 Association. Another early road, CA 1 (Route 1), first opened to traffic in 1912. It runs more than 548 miles along the Pacific Coast from just south of San Juan Capistrano in Southern California, north through the San Francisco Bay Area, to Leggett in Mendocino County. Running along some of the most beautiful coastline in the world, CA 1 has been designated an All-American Road by the Federal Highway Administration.

 highway construction equipment
Construction of US 50 between Folsom and Placerville, March 1940. US 50, which is also known as the "Backbone of America," stretches more than 3,000 miles from Sacramento over the high Sierra to Ocean City, Maryland and crosses through Lake Tahoe, Central Colorado, Carson City, Kansas City, St. Louis, Cincinnati, and Washington, D.C.

Nationwide highway systems did not originate with the Interstate Highway System, but predated it. The Lincoln Highway, first envisioned in 1913, was one of America’s most famous highways, affectionately known as “The Main Street Across America.” The highway, arguably the first transcontinental highway in the United States, crossed through 14 states and spanned more than 3,300 miles, coast-to-coast, from Times Square in New York City to Lincoln Park in San Francisco.

Another famous highway, Route 66, was one of the original federal routes, established on November 11, 1926. It ran 2,347 miles from Chicago through Missouri, Kansas, Oklahoma, Texas, New Mexico, and Arizona before ending at the beach in Santa Monica, California. Route 66, a major migratory road west, especially during the Great Depression, currently exists as Historic Route 66, a National Scenic Byway, and is commemorated, by various organizations along the way, including the California Historic Route 66 Association.

US 40 in Citrus Heights
US 40, Citrus Heights, Sacramento County, April 4, 1951. Parts of the Lincoln Highway often passed through small communities, such as this, throughout the nation as it stretched out across 13 states from San Francisco to New York City.
Route 66, 1926
Route 66, 1926
Construction of Redwood Highway, US 101 north of San Francisco
Construction of the Redwood Highway, US 101, north of San Francisco.

US Route 101, established in 1926, stretches 1,540 miles north from Los Angeles to Olympia, Washington. From Southern California to the San Francisco Bay Area, it follows much of the route of El Camino Real, the “royal road” of California’s Spanish- and Mexican-era missions, while north of San Francisco it becomes the famed Redwood Highway.

Other California highways built before the Federal Highway Act of 1956 include the 1940 Arroyo Seco Parkway between Pasadena and Los Angeles, and I-80, built in 1947, which connects San Francisco through Sacramento over the Sierra to Nevada. In addition, portions of I-105, the Santa Ana Freeway; I-205, the Tracy-Altamont expressway; and the Livermore Bypass and Altamont Bypass, I-580, all predated 1956.

 Construction of the Arroyo Seco Parkway
Construction of the Arroyo Seco Parkway, September 1938. Construction of the parkway, seen here off Avenue 43 Bridge, began in 1938 and completed by 1940.

The Interstate Highway System in California

Of the 1,000-mile increase in highway miles authorized nationally in the 1956 Federal-Aid Highway Act, none went to California. The state, however, did receive aid for 1,938 miles under the original designation of routes in 1947, as authorized under the 1944 Federal-Aid Highway Act, and for several additional “belt-line and circumreferential” routes in the San Francisco and Los Angeles areas. All together, this brought California’s total allocation up to 2,135 miles at the time of the 1956 Act.

I-580, May 19, 1937. I-580 is shown here between Dublin and Castro Valley after road widening construction.

Exactly which segments of California’s highways first utilized Interstate Highway System funding is hard to determine because California had already developed limited access highways to full freeway standards as far back as 1939, following the passing of the State’s Freeway Law. For example, the Aliso Street Viaduct (later part of 1-5) opened in 1948, and the Arroyo Seco Parkway (Route 110), the first freeway in California, opened in 1940, although it is not officially part of the Interstate Highway System.

Traffic on the Harbor Freeway
Traffic on the Harbor Freeway, I-110, July 24, 1958.

Other pre-1956 routes included the I-105 (Santa Ana Freeway), I-205 (North Tracy Bypass), and I-110 (Harbor Freeway).

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