The Eads Bridge is a rail and road bridge that crosses the Mississippi River in the city of St. Louis (Missouri) , connecting it to East St. Louis in Illinois , United States .
The bridge is named after its designer and builder, engineer James Buchanan Eads . In 1874, when its construction was completed, it was the longest arch bridge in the world , with a total length of 1,964 m. The grooved steel arch spans were considered bold. It was the first bridge of significant size built with steel. The mathematics professor William Chauvenet (1820-1870) collaborated with Eads by verifying and revising the calculations that served to design the bridge.
The Eads bridge was also the first to be built using only the cantilever system and one of the first
