The Pasadena Freeway (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 by the end of 1940. It is designated as a State Scenic Highway, National Civil Engineering Landmark, National Scenic Byway and is listed in the National Register of Historic Places.
The first segment of the freeway opened on December 10, 1938, stretching for just under a mile between the northern-most point on Glenarm Street in Pasadena and Fair Oaks Avenue in South Pasadena. The next segment opened on July 20, 1940, stretching about 3.7 miles between Orange Grove Avenue in South Pasadena and Avenue 40 in Los Angeles. The third segment to open was on December 30, 1940, stretching about 1.25 miles between Avenue 40 and the Figueroa Street Viaduct (at about Avenue 22, close to the present-day 5/110 interchange). The final segment, running just over half a mile through South Pasadena, between Fair Oaks and Orange Grove Avenues, was completed on January 30, 1941.