The Lake Pontchartrain Causeway, sometimes only the causeway, is a fixed link composed of two parallel bridges crossing Lake Pontchartrain in southern Louisiana, United States. The longer of the two bridges is 23.83 miles (38.35 km) long.

The southern terminus of the causeway is in Metairie, Louisiana, a suburb of New Orleans. The northern terminus is at Mandeville, Louisiana.

Since 1969, it was recognized as the longest bridge over water in the world; in 2011, in response to the opening of the longer Jiaozhou Bay Bridge in China, There are two categories for bridges over water: continuous and aggregate lengths over water.

Lake Pontchartrain Causeway then became the longest bridge over water (continuous) while Jiaozhou Bay Bridge the longest bridge over water (aggregate). 

The bridges are supported by 9,500 concrete pilings. The two bridges feature a bascule, which spans the navigation channel 8 miles (13 km) south of the north shore.

According to en.wikipedia