It once was the Earth’s tallest dam.

It once was the Earth’s tallest dam.

Rising 726.4 feet, Hoover Dam was the world’s tallest dam when it was built in the 1930s. These days, it’s the second-tallest dam in the U.S., having been surpassed by the 770-foot-high Oroville Dam in Northern California in 1968. The globe’s tallest dam is the 1,001-foot-high Jinping-I Dam in Liangshan, Sichuan, China, which became operational in 2013. Hoover Dam’s power plant was the world’s largest hydroelectric station from 1939 to 1949. It has an installed capacity of 2,080 megawatts (MW) and currently generates around 4 billion kilowatt-hours (kWh) of hydroelectric power annually, for homes and business in Nevada, Arizona and California. China’s Three Gorges Dam, which started generating electricity in 2003 and became fully functional nine years later, is considered the planet’s largest hydroelectric dam, with a capacity of 22,500 megawatts. In 2014, Three Gorges broke the global record for annual hydroelectric power production, generating 98.8 billion KWh of electricity. The biggest hydropower producer in the U.S., Washington State’s Grand Coulee Dam, completed in 1941 (a third power station was added in 1974), has a capacity of 6,809 MW and generates about 21 billion kWh of electricity each year.