At 23.87 miles long, the Lake Pontchartrain Causeway is the world's longest bridge over water. The first span was completed in August 1956. Due to increased traffic, a second span opened in May 1969. The Causeway piloted major construction of prefabricated, prestressed concrete bridges in the United States. It is supported by more than 9,000 pilings. Construction of the Causeway expanded the Greater New Orleans area to include the northshore of Lake Pontchartrain.