The Lake Pontchartrain Causeway is the longest continuous bridge over water in the world. It stretches for 38 kilometers (24 miles) and is supported by around 9,500 concrete pilings.

The southbound portion of the Lake Pontchartrain Causeway, which had two lanes, was first opened on August 30, 1956, while the northbound bridge was completed in 1969. The bridge was designed to connect the urban area of New Orleans, Louisiana, with the communities on the other side of Lake Pontchartrain. 

Despite its enormous size, construction of the bridge only took 14 months, with assembly-line and mass-production methods. In fact, this was the first time that such construction methods were applied to a bridge.

During the 1940s and 1950s, New Orleans went through a growth spurt, but access to the city was hindered by the lake. To reach the city from the north shore required a lengthy, time-consuming drive. As such, the Greater New Orleans Expressway Commission was established to build the Lake Pontchartrain Causeway Bridge.

The bridge was a success, benefiting those who lived on either side of the lake. Commute times were dramatically cut, while the bridge also offered access for tourists in New Orleans to visit restaurants and retail stores on the north shore.

The southbound bridge consists of 2,246 decks (spans), which are around 8.5 meters (28 feet) wide and 17 meters (56 feet) long, while the northbound bride has 1,506 spans, which are typically 8.5 meters (28 feet) wide and 25.6 meters (84 feet) long. The spans include monolithically-cast (meaning that all components were cast together at the same time) precast prestressed concrete girders, rails, and decks

The spans on both the northbound and southbound bridges are supported by precast pile bents that average 27.4 meters (90 feet) in length.

While the Lake Pontchartrain Causeway held the Guinness World Record for the longest bridge over water in the world, its status was challenged in 2011 with the opening of the Qingdao Jiaozhou Bay Bridge in China. However, controversy over this led to the creation of two categories for bridges over water. So now the Lake Pontchartrain Causeway is recognized as the longest “continuous” bridge over water, while the Jiaozhou Bay Bridge is regarded as the longest “aggregate” bridge.