The Great Unknown

In the summer of 1869, an expedition embarked from The Green River Station in the Wyoming Territory and traveled downstream through parts of the present-day states of Colorado, Utah, and Arizona before reaching the convergence of the Colorado and Virgin rivers in present-day Nevada. Despite a series of hardships, including losses of boats and supplies, near-drownings, and the eventual departures of several crew members, the voyage produced the first detailed descriptions of much of the previously unexplored canyon country of the Colorado Plateau.
Today, American Naturalist John Wesley Powell, and the Grand Canyon National Park.