The current portals are not original; they were built when the upstream span was widened in 1915. The original bridge was designed by Gustav Lindenthal; the current portals were designed by Stanley L. Roush, who was responsible for many prominent transportation-related projects, including the entrances to the Liberty Tubes and Armstrong Tunnel and the terminal at the Allegheny County Airport.

The bridge is the oldest through-truss bridge in the United States, and one of very few with a Pauli or lenticular truss. The piers are even older; they were reused from the previous bridge, designed by John Roebling after the Great Fire of 1845 destroyed the old wooden covered bridge that had been put up in 1818.