The bridge is named for James Buchanan Eads, who designed and built it. Work began in 1867 and ended in 1874. Eads had no experience building bridges. It was the first bridge across the Mississippi south of the Missouri River, and it is the oldest bridge on the river.
The foundations went more than 100 feet below the water, deeper than anything built underwater before. They used pneumatic caissons, the largest ever built at the time. The center arch is 520 feet long, the longest rigid span in the world then.
The highway deck was closed to cars from 1991 to 2003 and now carries cars and people again. The old railroad deck carries the MetroLink light rail.