The Pasadena Freeway (Interstate 110), or “Arroyo Seco Parkway” as it was originally called, is on the U.S. National Register of Historic Places as the first freeway in the Western United States. The first segment was opened to traffic in 1938 with most of the rest of the freeway opening on December 30, 1940.

It appears that a section of the freeway connecting Orange Grove Avenue with Avenue 40 opened on July 20, 1940. Above is a panoramic view of Highland Park looking northeast from Pasadena Avenue (formerly North Figueroa Street) between Avenue 40 and Avenue 41, ca.1880-1888. Train tracks from the Santa Fe railroad are visible past the brush in the foreground at Pasadena Avenue and Dayton Avenue, beyond which a field with trees evenly spaced is Highland Park. Behind this to the extreme left, the residence of Judge D.P. Hatch is partially visible, a white spot of exterior wall. More, larger houses are visible to the right behind the park, standing in front of a ridge of hills. One of these houses is the old Potts home.

Today, the Arroyo Seco Parkway remains much as it was in 1940, even though it wasn’t designed for the speeds that motorists travel today: There are no acceleration and deceleration lanes, and drivers must go from the on-ramp speed of five miles per hour up to the freeway speed of 55 in a short and hair-raising distance. It was intended to carry about 27,000 cars a day; today, it sees closer to 122,000. But it’s still the most direct route from Pasadena into downtown Los Angeles.

The 110 Interstate is distinguished by another ‘first’ by being a part of the Bill Keene Memorial Interchange, the first stacked interchange constructed in the world. The Four Level Interchange was completed in 1949 and fully opened in 1953. CHS holds in its collection the James B. Case Slides of Highway Construction in California (1949-1953) documenting construction of highways in Los Angeles, Orick, and San Francisco, California. The bulk of the collection shows the construction and completion of the Hollywood Freeway and the Harbor Freeway in Los Angeles and the Bayshore Freeway in the San Francisco Bay Area. A selection of images, like the one shown above, depict the final stages of construction of the Four Level Interchange in Los Angeles.

—Wendy Welker, California Historical Society Archivist

This post was originally published on July 25, 2012 and was updated on July 7, 2023.