How Sepulveda Canyon Became the 405 | KCET
How Sepulveda Canyon Became the 405
Today a river of concrete passes through Sepulveda Canyon, one of the three main portals between the San Fernando Valley and the Los Angeles Basin. But as recently as 1934 that mighty river – the 405 freeway – was only a modest stream, a winding, unpaved road that snaked through the Santa Monica Mountains.
More Freeway History
For centuries the region’s native Tongva people had hiked a faint footpath through Sepulveda Canyon, and in 1769 the soldiers and clergy of Spain’s Portola expedition followed that ancient trade route on their way to Monterey. Trail became road in 1875, when the two wheat barons of the San Fernando Valley, Isaac Lankershim and Isaac Newton Van Nuys, widened the footpath to allow for the passage of sturdy wagons laden with grain and bound for ships docked at the Santa Monica Pier. But when the Southern Pacific soon lowered its freight rates, the wheat ranchers instead sent their harvest by train to San Pedro. The new, neglected road eroded into the hillsides.
Eventually, booming development in the San Fernando Valley during the 1920s persuaded the city and county to rebuild the road for automobiles. Traffic was overwhelming the two established routes between the Valley and the Basin, Cahuenga Pass and San Fernando Road, both of which were out of the way for residents of faraway Van Nuys and Owensmouth. New Sepulveda Boulevard – a 50-mile highway stretching between San Fernando and Long Beach – would provide the Valley with a more direct link to the Basin and harbor beyond at San Pedro Bay.
Construction lasted several years and culminated with the opening of a 650-foot tunnel beneath the summit at Mulholland Drive, an event the city celebrated with a grand Spanish-style fiesta. Despite the festivities, by the time traffic started flowing in September 1930, the new Sepulveda Canyon Road was already inadequate. Five years later the state spent $275,000 to pave it, and by the late 1950s traffic engineers had envisioned an audacious construction project that just might keep traffic flowing freely over Sepulveda Pass forever.
The engineers’ plan? Tear Sepulveda Canyon apart and then rebuild it to allow a superhighway to pass through. Beginning in August 1960, earthmovers carved a gorge 1,800 feet wide and 260 feet deep through the mountains, accomplishing in two years what might take natural erosional forces two million. The bulldozers' total haul: 13 million cubic yards of slate, shale, and dirt. Workers then built massive retaining walls to keep the unnaturally steep slopes from slipping and reconfigured the area's natural drainage through a series of culverts. By 1962, an eight-lane concrete freeway with a maximum grade of 5½% sliced through the mountains.
Though traffic did flow freely at first, the San Diego Freeway (originally signed as California 7 and later redesignated Intestate 405) eventually became one of the Southland’s most hated stretches of pavement. And so the work Lankershim and Van Nuys began in 1875 to improve an ancient trail continues to this day. Regional planners are now considering a menu of options – including an underground toll road, a subway, even a monorail – to relieve congestion, and in 2015 Metro completed a five-year, $1.1 billion project to widen the canyon’s concrete river and its artificial gorge.
A version of this story first appeared on Los Angeles Magazine's website on March 12, 2014. It has been updated here with additional images and information.
The closure of migrant learning centers in the southern province of Ranong has driven hundreds of Burmese children into work.
The COVID-19 and economic crisis have thrown plans to deliver more ambitious climate plans off track — but delay is dangerous, vulnerable nations say.
Take a trip into the Autry’s empty galleries to watch another intimate acoustic performance — this time featuring the soulful voice of Chris Pierce — as part of the museum’s "Best of Los Angeles" series.
A small company is set on forging ahead with plans for a proposed coal mine near South Africa’s Kruger National Park, despite the public's concerns of environmental threats.
- 1 of 372
- next ›
Griffith Park is one of the largest municipal parks in the United States. Its founder, Griffith J. Griffith, donated the land to the city as a public recreation ground for all the people — an ideal that has been challenged over the years.
During World War II, three renowned photographers captured scenes from the Japanese incarceration: outsiders Dorothea Lange and Ansel Adams and incarceree Tōyō Miyatake who boldly smuggled in a camera lens to document life from within the camp.
Prohibition may have outlawed liquor, but that didn’t mean the booze stopped flowing. Explore the myths of subterranean Los Angeles, crawl through prohibition-era tunnels, and visit some of the city’s oldest speakeasies.
Although best known for designing the homes of celebrities like Lucille Ball and Frank Sinatra, the pioneering African-American architect Paul Revere Williams also contributed to some of the city’ s most recognizable civic structures.
As recently as a century ago, scientists doubted whether the universe extended beyond our own Milky Way — until astronomer Edwin Hubble, working with the world’s most powerful telescope discovered just how vast the universe is.
- 1 of 5
- next ›