December marked the anniversary of the opening of the Arroyo Seco Parkway between Los Angeles and Pasadena, California. Opened to traffic December 10, 1938, and completed December 30, 1940, the Arroyo Seco Parkway, also known as the Pasadena Freeway, represents the transitional phase between early parkways and modern freeways.
Arroyo Seco, meaning “dry stream” in Spanish, is an intermittent stream channel from the San Gabriel Mountains to the Los Angeles River. Dating back to the original inhabitants of the area, the Arroyo Seco Canyon has since served as a major transportation corridor. The first known survey for a permanent roadway through the Arroyo Seco was in 1895. Shortly thereafter, the California Cycleway Company purchased a 6-mile right-of-way between downtown Pasadena and Los Angeles. In 1899, construction began on a 1-mile elevated wooden bikeway, which opened on January 1, 1900. Within a decade, the structure was dismantled and the Pasadena Rapid Transit Company acquired the right-of-way.
Subsequent transportation plans for the Arroyo Seco Canyon included a roadway. Some people, particularly those backed by the Automobile Club of Southern California, encouraged a fast road connecting the 2 cities. Others, influenced by the City Beautiful movement, concentrated on the landscape. In 1924, the landmark publication “Major Traffic Street Plan – Los Angeles, California,” suggested that a new parkway be built for traffic relief and to provide motorists with a “great deal of incidental recreation and pleasure.” By the 1930s, traffic engineers promoted the concept of roads existing only for automobiles, with grade-separated intersections, limited access to adjacent properties, and no interaction with pedestrians, trolleys, horses, or bicyclists. Los Angeles City Engineer Lloyd Aldrich became a strong advocate for the freeway concept after he took over leadership of the Bureau of Engineering in 1933.
Aldrich found guidance in East Coast highways and Robert Moses’ New York City parkway system. The Arroyo Seco Parkway was envisioned as a scenic pleasure road and a vital transportation artery linking Los Angeles and Pasadena. The highway was originally designed with two 11–12-foot lanes and one 10-foot shoulder in each direction, with the wider lanes paved in black asphalt and the outside lanes paved in grey concrete. The engineers used a design speed of 45 miles per hour and incorporated many parkway characteristics, including using mostly native roadside plants.
Construction on the Arroyo Seco Parkway began with a groundbreaking ceremony in South Pasadena on March 22, 1938. The first segment, less than a mile long from Pasadena to South Pasadena, was opened to traffic December 10, 1938. By 1939, the state decided to replace the shoulders with additional travel lanes for increased capacity. The final segment in Los Angeles was opened December 30, 1940, just in time for Pasadena’s Tournament of Roses festivities.
When the Arroyo Seco Parkway opened, it was the first section of roadway for what was to become the Los Angeles metropolitan area freeway system. It also served as a prototype for urban freeways throughout the United States. At the time, it was considered an engineering marvel, reducing travel time between Los Angeles and Pasadena from 27 to 12 minutes. The 6-lane, 6-mile highway designed for 27,000 automobiles a day now carries more than 122,000 cars daily. Despite a quadrupling of traffic volumes, the original roadway north of the Los AngelesRiver largely remains as it was when it opened in 1940.
Arroyo Seco Parkway was dedicated as an ASCE National Historic Civil Engineering Landmark in 1999.