California's Highest Span: The History and Legacy of the Foresthill Bridge

Spanning 2,428 feet across the North Fork of the American River near Auburn, California, the Foresthill Bridge is an engineering landmark that commands attention. Its deck hangs 730 feet above the canyon floor, making it the highest bridge in California and the fourth-highest in the United States. Its support piers are so vast that they stand only 16 feet shorter than the main towers of San Francisco's Golden Gate Bridge. Yet for a structure of such immense scale, the traffic crossing it is remarkably modest. The story behind why this massive steel cantilever bridge was built in the Sierra Nevada foothills is one of the most unusual chapters in modern American infrastructure.

Gold Rush Origins

Long before the modern bridge existed, the surrounding Placer County region was shaped by the California Gold Rush. In 1850, gold was discovered along a ridge between the North and Middle Forks of the American River, leading to the establishment of the town of Foresthill. By the mid-1850s, Foresthill had grown into a major mining hub, requiring reliable transportation routes down to Auburn and the Sacramento Valley. For over a century, travelers crossed the river canyon via narrow, winding roads and modest low-water bridges that were routinely susceptible to seasonal flooding.

The Auburn Dam & Bridge Construction

That dynamic changed dramatically in the late 1960s with the rise of the Central Valley Project, a federal infrastructure initiative led by the U.S. Bureau of Reclamation. The Bureau planned to construct the Auburn Dam downstream—a colossal concrete arch dam designed to control flooding, supply irrigation water, and generate hydroelectric power. Had it been completed, the dam would have created a reservoir holding more than two million acre-feet of water, flooding the deep river canyons beneath it.

Because the proposed 600-foot-deep reservoir would submerge the existing river-level crossing, federal planners determined that a replacement bridge was necessary to keep the town of Foresthill connected to Auburn. Engineers designed a massive steel deck truss bridge elevated high enough to clear the future waterline. Steel components were fabricated in Japan by Kawasaki Heavy Industries in 1971, shipped across the Pacific, and assembled on site by Willamette Western Contractors.

When the bridge opened on Labor Day in 1973 at a cost of roughly $13 million, crowds gathered to celebrate. The design anticipated that the rising lake waters would eventually leave the bridge deck resting a mere 130 feet above water level. However, the reservoir never materialized.

Seismic Concerns and Project Abandonment

In August 1975, a magnitude 5.7 earthquake struck near Oroville, California. The seismic event prompted geologists and engineers to re-examine the structural safety of the planned Auburn Dam. Studies revealed that the dam site was situated directly on active earthquake fault lines, sparking intense public debate, environmental opposition, and political gridlock. Construction on the dam was halted, and the project was ultimately abandoned.

As a result, the Foresthill Bridge remained suspended high above a dry, green canyon rather than a deep blue lake. Underneath the bridge, anti-dam slogans painted by 1970s protesters remain visible on the steel girders—a silent reminder of the environmental debates that reshaped California water policy.

Cultural Legacy & Modern Era

Over the decades, the bridge developed its own distinct cultural identity. In 2002, it achieved cinematic fame when it was featured in the opening action scene of the Hollywood film 'xXx'. In the sequence, a stunt driver launched a red Chevrolet Corvette off the bridge while a stunt double base-jumped from the falling vehicle and parachuted into the canyon below.

Beyond Hollywood, the bridge became a focal point for local traditions. For decades, pedestrians walking along the narrow sidewalks etched declarations of love, names, and dates into the paintwork, transforming the railings into a folk archive of local relationships.

Between 2011 and 2015, Placer County conducted a major $74.4 million seismic retrofit and restoration project. The project reinforced the steel framework to withstand major earthquakes, repainted the structure, and replaced the original four-foot railings with higher eight-foot safety barriers.

Today, the Foresthill Bridge stands as both a functional thoroughfare and a monument to an era of grand public works. It continues to draw hikers, runners, and visitors who come to take in sweeping views of the Auburn State Recreation Area, marveling at an engineering project built for a lake that never came to be.