From pre-colonial times to the post-industrial age, rivers have shaped the course of American history and culture. Take a fascinating historical journey down the greatest rivers in the United States and learn how they have influenced the people and communities that live and work on them. The histories of these rivers include many of the notable names in American history, such as Lewis & Clark, John Colter, Zebulon Pike, and Tecumseh. The Colorado is the most important river in the entire region of the American Southwest. Without the water of the Colorado, whole modern-day communities in the west, from Phoenix to Tucson to Las Vegas, would likely not survive.