Huey P. Long Bridge (Also known as The Old Mississippi River Bridge, or the Huey P. Long - O.K. Allen Bridge, or the Airline Highway Bridge), Louisiana

In order to cross the Mississippi River, while enabling large vessels to pass underneath, trains begin a long, slow climb from the near sea-level swamps of southern Louisiana, two miles away from the river itself. The structure that allows this is part of one of the longest railway bridges in the USA, named after and commissioned by Mr. Long, the notorious Louisiana governor. Construction began in 1937, and was completed in 1940. The bridge was designed to carry four lanes of automobile traffic, as well as one railroad track. The thick sediment of the riverbed required the construction of a cement foundation extending 170 feet beneath the water and mud. Despite nearly 800 feet of horizontal clearance between the piers of its cantilever truss, it has been struck by ships several times. Since its construction, the bridge has undergone two major rehabilitation efforts, one between 1986-1987, and the other between 2012-2016. As of 2017, average daily traffic across the bridge is around 18,600 vehicles.