Built to Last – the Oldest Working Bridge on the Mississippi

Missouri History Museum – St. Louis, MO


Eads Bridge in St. Louis is a feat of engineering that remains the oldest bridge crossing on the Mississippi River, at over 145 years old, people still cross it today.  As much as it was a marvel, it was also a deathtrap for many of the workers.  The Missouri Historical Society dug into what happened (pardon the pun).

James B. Eads, ca. 1884. Missouri Historical Society Collections.

James B. Eads, ca. 1884. Missouri Historical Society Collections.

~Eads Bridge​~

In the 1860’s when project engineer and designer, James B. Eads, began building the bridge many people thought it was an impossibility.  To build a bridge across an active river that saw a million people a year in and out of St. Louis, without disrupting the river trade, seemed unlikely.   In addition Eads needed workers to dig 50 feet below the bed of the river to hit bedrock.

Eads Bridge

Dr. Alphonse Jaminet, 1870. Missouri Historical Society Collections.

~Digging Deep~

Eads utilized a form of a diving bell, called a caisson, to allow workers to dig into the Mississippi River bed. But to hold back the river, the air pressure in the caisson had to be increased to 40 times what it is on the surface.  Workers talked about squeaking voices and the strange way the candles burned.  Three years into the construction of the bridge, worker James Riley emerged from the caisson gasping for air. Within 15 minutes, he was dead. By week’s end, four more workers had died.

Eads Bridge

~Decompression Sickness~

Works in the caissons were dealing with decompression sickness, or the bends. Nitrogen was becoming trapped in their bloodstream and boiling as they climbed the stairs to the surface. Workers were spitting up blood, having excruciating pain in their limbs and stomachs, or having their legs go numb.  In total 119 workers were affected by the illness and 14 died. What was happening to them was a mystery and Eads brought in his own physician to set up a floating hospital at the pier site.

Eads Bridge

~​Slow Decompression~

Although Eads’ doctor, Dr. Alphonse Jaminet never quite understood what was happening to the workers, he did discover that gradual decompression was vital and his principles are still used today by divers.  Eads Bridge was built to stand as long as St.Louis believed it to be of use to the city and cars still drive over the bridge, the metro train clambers along on the lower level, and walkers and bicyclists traverse the bridge for a unique view of the St. Louis skyline.


Learn more about the Eads Bridge in this video, featuring David Lobbig, Curator of Environmental Life at the Missouri Historical Society.

The Missouri Historical Society’s Mighty Mississippi exhibit and related content is sponsored by Bank of America.


The museum is free to the public and perfectly located for a full day exploring St. Louis.  The Muny, the St. Louis Zoo, and the World Fair Pavilion are all nearby neighbors within Forest Park.

Missouri History Museum

St. Louis, MO 63112