| Manchac Swamp Bridge | |
|---|---|
| Other name(s) | I-55 Manchac Swamp Crossing |
| Carries | Interstate 55 |
| Crosses | Manchac Swamp |
| Locale | St. John the Baptist Parish / Tangipahoa Parish, Louisiana, USA |
| Maintained by | LA DOT |
| Total length | 36,710 meters (120,400 feet) |
| Opened | 1979[1] |
The Manchac Swamp Bridge is a twin concrete trestle bridge[1] in the US state of Louisiana. With a total length of 22.80 miles (36.69 km) it is one of the longest bridges in the world over water. The bridge carries Interstate 55 over the Manchac Swamp in Louisiana, and represents one-third of the highway's approximately 66 miles in Louisiana. Opening in 1979,[1] its piles were driven 250 feet (76 m) beneath the swamp and with the cost of the span being $7 million per mile to complete.[2]