150 years ago, the Eads Bridge became the first steel bridge to cross the Mississippi River—a marvel of 19th-century engineering that forever changed the landscape of St. Louis. Built by Keystone Bridge Company, a precursor to American Bridge, it remains one of the most iconic and enduring pieces of American infrastructure. 

The Need for a Grand Crossing 

Following the Civil War, St. Louis needed a bold solution to keep pace with booming commerce and the rise of railroads. Without a reliable crossing of the Mississippi, the city risked falling behind Chicago as the Midwest’s primary hub. Enter James Buchanan Eads, a self-taught engineer who had never built a bridge but was trusted with designing one of the most ambitious projects of the era. 

Pioneering Steel Construction 

The Keystone Bridge Company, founded by Andrew Carnegie, was contracted to erect the steel superstructure. At the time, the use of steel in bridge building was unheard of. Keystone’s expertise and innovative fabrication methods made the bridge possible, laying the groundwork for the steel construction boom that followed. 

Engineering a First-of-Its-Kind Structure 

Construction began in 1867 and introduced multiple groundbreaking techniques: 

• First large-scale use of steel in a bridge. 

• Three massive arches spanning 502, 520, and 502 feet. 

• Granite piers sunk 123 feet into the riverbed using pneumatic caissons—a record-setting depth at the time. 

• Wrought iron tubes reinforced with chrome steel for strength and flexibility. 

The result was a bridge unlike anything built before—an architectural triumph that blended Roman-inspired arches with modern materials. 

Challenges on the River 

The Mississippi’s powerful currents, unpredictable weather, and opposition from steamboat operators pushed the project to its limits. Workers faced harsh conditions in pressurized caissons, with many falling victim to “caisson disease” (now known as decompression sickness). Fifteen workers died, and dozens more were injured—a sobering reminder of the risks of early engineering feats. 

A Grand Opening 

Completed in 1874 at a cost of nearly $10 million, the bridge debuted with a show of strength. Fourteen locomotives paraded across the structure, followed by the unforgettable sight of a circus elephant crossing to prove its durability. President Ulysses S. Grant himself presided over the dedication on July 4, 1874. 

Legacy and Preservation 

Though the Eads Bridge initially struggled financially, it became a vital link in the region’s transportation network and a lasting symbol of innovation. 

Designated a National Historic Landmark in 1964, the bridge underwent a $48 million restoration completed in 2016, ensuring it will serve the region until at least 2091. Today, it carries both Metrolink light rail and motor traffic while standing as a living monument to American ingenuity. 

Why It Matters Today 

The Eads Bridge was more than a crossing—it was a turning point in engineering history. Its successful use of steel set the stage for future superstructures, including the great bridges of the 20th century. Thanks to Keystone Bridge’s pioneering work, the industry was forever changed. 

The Eads Bridge isn’t just 150 years old—it’s 150 years strong. A testament to vision, resilience, and the enduring power of great engineering.