Part 1 of this four-part series on major American public works projects, looks at efforts to tame the Mississippi and Colorado, rivers with opposite challenges. With the Mississippi, it's flood control; with the Colorado, it's providing water for the arid West. The Hoover Dam, construction of which is followed here, took care of that, and provided electricity as well. In the Midwest, flood-control efforts began in earnest after disastrous 1927 flooding. Coordinating relief efforts: Herbert Hoover, "the great engineer." Stacy Keach narrates.