Structures That Shape the Rivers

Beginning in the 1940s, the Bureau of Reclamation sought to dam US rivers to harness their power and create water reservoirs for communities. Today there are an estimated 84,000 dams across the United States. Some—such as Hoover Dam—are located within national parks. Dams provide valuable resources like hydropower and water, but they have a complicated history. Learn more about the history of dams and the role they play in shaping America’s landscapes and powering its communities.

Map of the United States showing all units of the National Park System

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Last updated: February 5, 2019