I-55 is a major highway through the New Orleans metropolitan area, the city being located east of the junction between I-10 and I-55. It also serves as an important hurricane evacuation route for the region. I-55 was opened in several stages beginning in 1960 with a bypass of Ponchatoula and Hammond. The southern of I-55, consisting of a twin-span viaduct through the Manchac swamp, was completed in 1979 and is one of the longest bridges in the world.
