Manchac Swamp Bridge

The Manchac Swamp Bridge is a road bridge in St. John the Baptist Parish, Louisiana, that runs for nearly 37 kilometers (about 23 miles) through wetlands, resting on concrete piers that rise above the dark water. The roadway stretches almost perfectly straight, offering clear views of cypress trees, shallow swamp water, and occasional turtles resting on logs.

The bridge was built in the late 1970s to create a faster route through the Louisiana swamps and officially opened to traffic in 1979. Its construction required deep foundation piles because the ground consists of soft peat and mud that could not support conventional foundations.

The name Manchac comes from a word referring to the waterways in this region, where fishing boats and airboats pass every day. On calm days you can see people on the banks casting lines or pulling crab traps from the water, just as they have done for generations.

The bridge carries two major highways across the swamp and stays open to all types of vehicles throughout the week. In fog or heavy rain it is wise to drive slower and keep your lights on, because visibility can drop sharply along the long straight stretch.

The design uses continuous concrete piers rather than traditional bridge arches, keeping the roadway at a steady height for its entire length, floating just a few meters above the water level. On windless days the structure reflects in the still water, visually doubling its presence in the landscape.

Location: Louisiana

Inception: 1979

Official opening: 1979

Height: 15 m

Length: 36,710 m

GPS coordinates: 30.30290,-90.40580

Latest update: December 5, 2025 22:25