Where is the world's longest beam bridge?

As of 2014, the largest beam bridge in the world is the Lake Pontchartrain Causeway in Louisiana. Northbound, the bridge span is 23.87 miles long while the southbound span is 23.86 miles long.

The Lake Pontchartrain Causeway opened as a two lane span in 1956 and cost $30.7 million to build. In 1969 the parallel two lane span opened after $26 million in building costs. The spans are 80 feet apart and are connected by seven crossover areas which can be used for emergency stopping. As of 2014, The Lake Pontchartrain Causeway is recognized by Guinness World Records as the longest bridge over water in the world since 1969.