<P> The original Causeway was a two - lane span, measuring 23.86 miles (38.40 km) in length . It opened in 1956 at a cost of $46 million . This included not just the bridge, but three approach roads on the north end and a long stretch of road on the south end . A parallel two - lane span, 1 / 100th of a mile (15 m) longer than the original, opened on May 10, 1969, at a cost of $30 million . </P> <P> Since its construction, the Causeway has operated as a toll bridge . Until 1999, tolls were collected from traffic going in each direction . To alleviate congestion on the south shore, toll collections were eliminated on the northbound span . The standard tolls for cars changed from $1.50 in each direction, to a $3 toll collected on the North Shore for southbound traffic . In 2017, the toll was raised to fund safety improvements on the bridge . The toll changed from $3.00 with cash and $2.00 with a toll tag to $5.00 with cash and $3.00 with a Toll Tag . </P> <P> The opening of the Causeway boosted the fortunes of small North Shore communities by reducing drive time into New Orleans by up to 50 minutes, bringing the North Shore into the New Orleans metropolitan area . Prior to the Causeway, residents of St. Tammany Parish used either the Maestri Bridge on U.S. Route 11 or the Rigolets Bridge on U.S. Route 90, both near Slidell, Louisiana; or on the west side, via U.S. Route 51 through Manchac, Louisiana . </P> <P> After Hurricane Katrina on August 29, 2005, videos collected showed damage to the bridge . The storm surge was not as high under the Causeway as it was near the I - 10 Twin Span Bridge, and damage was mostly limited to the turnarounds . A total of 17 spans were lost . Structural foundations remained intact . The causeways have never sustained major damage of any sort from hurricanes or other natural occurrences, a rarity among causeways . The existing fiber optic cable plant was blown out of its tray but remained intact per optical time domain reflectometer (OTDR) analysis . With the I - 10 Twin Span Bridge severely damaged, the Causeway was used as a major route for recovery teams staying in lands to the north to get into New Orleans . The Causeway reopened first to emergency traffic and then to the general public--with tolls suspended--on September 19, 2005 . Tolls were reinstated by mid-October of that year . </P>

The longest bridge over water in the united states