Franklin D. Roosevelt

For 12 million years it trickled, meandered, and snaked, before bursting violently loose to slash to its final destination. Then, one winter day in 1935, this ancient, tempestuous journey abruptly ended in a remote canyon as the last of more than 5 million buckets of concrete was poured onto the crest of a 726-foot wall that blocked its path. Observers watched in awe as the nation’s wildest river puddled up behind the massive structure. Soon the benign-looking pond would reach back for 115 miles to a depth of 500 feet, the largest human-made lake in the world.