Louisiana has historically been a leader in the oil and gas industry. While still heavily dependent on oil & gas, Louisiana companies are moving forward in developing alternative energy sources. The oil & gas industry began in Louisiana in the late 19th century when gas was discovered in northern Louisiana. Today, oil & gas is one of the state's leading industries in terms of economic impact, tax revenue and employment. Eighty-eight percent of U.S. offshore rigs are located on Louisiana's Outer Continental Shelf and, counting offshore production, the state is the No. 1 producer of crude oil and the No. 2 producer of natural gas in the country.