The rivers of the American West have shaped the pattern of human development across the region. In turn, human activities are rapidly changing the rivers that sustain them.
Today, nearly half - 49% - of all river miles in the West are no longer in their natural state. In all, 140,000 miles of rivers in the American West – a distance long enough to circle the Earth nearly 6 times – have been modified by dams, diversions, suburban sprawl, legacy mines, and other human development.
Click anywhere on the map to explore how and why rivers in the West are changing and disappearing. You can also use the navigation tools at the top right of this page.