John Wesley Powell (March 24, 1834 – September 23, 1902) was an American geologist, U.S. Army soldier, explorer of the American West, professor at Illinois Wesleyan University, and director of major scientific and cultural institutions. He is famous for his 1869 geographic expedition, a three-month river trip down the Green and Colorado rivers, including the first official U.S. government-sponsored passage through the Grand Canyon.