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The Arroyo Seco, Rockets, and the Growth of Los Angeles

October 03, 2012

AAG Annual Meeting, April 9-13, 2013, Los Angeles

On October 31, 1936, five students from Caltech’s Guggenheim Aeronautical Laboratory attempted to test fire a small rocket motor in an isolated and dry canyon wash at the foot of the San Gabriel Mountains in Southern California. With the encouragement of California Institute of Technology professor Theodore von Karman, the young “rocket boys” encountered success with their experiment two weeks later. For the next few years they continued their noisy and often dangerous pursuit on the Caltech campus approximately seven miles southeast of the original test site. By 1940, Professor von Karman had established a new facility with tarpaper shacks on the other side of the dry wash from the original tests. As the first director of this new venture in 1943, von Karman named it the Jet Propulsion Laboratory (JPL).

Arroyo SecoThe Arroyo Seco today with JPL and the San Gabriel Mountains in the background. The 2013 AAG Annual Meeting will be held in Los Angeles, April 9-13. (Credit: Sandra Leduc)

Nearly 70 years later, NASA’s Jet Propulsion Laboratory is situated above the banks of the Arroyo Seco wash, at the base of the San Gabriel Mountains – one of the steepest and most active ranges in the country. In the last seven decades, JPL – in coordination with NASA and Caltech – has witnessed tremendous growth, currently employing 5,000 people and operating with a budget of 1.6 billion dollars. As it expanded throughout the twentieth century, JPL moved beyond early rocketry and began designing and executing robotic spacecraft for planetary exploration. Today, JPL rests on a bluff overlooking the original test site of the “rocket boys.” It is a massive property with dozens of buildings dedicated to exploring the solar system and beyond. The one constant amidst the expansion of JPL’s campus, and in many ways our global understanding of the universe, is that the Arroyo Seco served as a testing site for the first rockets.

The Arroyo Seco – referred to sometimes as a dry canyon wash – is a seasonal waterway or stream that begins its descent from the base of Strawberry Peak (6,000 feet), some 15 miles northeast of JPL. Unquestionably short on water most of the year, the Arroyo Seco stands in stark contrast to the regular rainfall and traditional stream patterns along the east coast. The Arroyo Seco is carved by infrequent, yet high impact storms that make their way inland from the Pacific, only to get stopped by the San Gabriel Mountains east of the LA basin. John Muir described this range as “…most ruggedly, thornily savage. Not even in the Sierra have I ever made the acquaintance of mountains more rigidly inaccessible.”

Where the Arroyo courses past JPL, the topography softens and the debris that falls from the canyon settles across a large area behind Devil’s Gate Dam. The Arroyo Seco becomes channelized at the Dam that was built in 1920, and embarks on a ten mile journey through the neighborhoods of Northeast Los Angeles. It ultimately converges with the Los Angeles River underneath two freeway overpasses and an adjacent Home Depot. Obscured by the freeways, adjacent streets, and industrial yards, the concrete channel of the Arroyo jettisons its runoff to the Los Angeles River, where it flows through downtown, and eventually out to the Pacific Ocean. Drivers and pedestrians go about their business with little knowledge of the confluence below.

Many of the neighborhoods that developed around this confluence arose because of the idyllic weather, swaying palms, and dynamic landscapes represented by features such as the Arroyo and the San Gabriel Mountains. In addition however, many came to L.A. for the jobs that were created directly or indirectly from the aerospace industry, as the “rocket boys” and their contemporaries built companies that relied on the skills of tens of thousands. Entering the Post-WWII years, these industrial concentrations of aerospace and other high-technology, defense-related industries expanded further from the center of Los Angeles. From 1940-1970, Los Angeles County grew from 2.8 million to 7 million residents, with many settling in brand new subdivisions that sprouted around the aerospace and high-tech industries that developed in the San Fernando Valley, LAX Airport area, and Orange County.

This incredible growth cannot be attributed solely to early experiments in rocketry and the subsequent development of aerospace and high technology. The construction of the Los Angeles aqueduct in 1913, real estate speculation, and myriad other forms of progress contributed greatly to the massive increases in population. Still, some of that growth does have its origins in the dry river bed of the Arroyo Seco. Throughout these explorations, the “rocket boys” and those who followed were always dependent on the geography of the landscapes below including the availability of the dry, wide-open riverbed. Whether it was for the idyllic landscapes such as the Arroyo, or the industry that was born in the Arroyo, Los Angeles has grown by capturing the imagination of millions.  

Lorne Platt
Central Connecticut State University 


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