This is a list of operational hydroelectric power stations in the United States with a current nameplate capacity of at least 100 MW. The Hoover Dam in Arizona and Nevada was the first hydroelectric power station in the United States to have a capacity of at least 1,000 MW upon completion in 1936. Since then numerous other hydroelectric power stations have surpassed the 1,000 MW threshold, most often through the expansion of existing hydroelectric facilities. All but two states of the United States are home to at least one hydroelectric power station, those without being Delaware and Mississippi.