When John Wesley Powell became the first person to navigate the entire Colorado River, through the Grand Canyon, he completed what Lewis and Clark had begun nearly 70 years earlier--the final exploration of continental America. The son of an abolitionist preacher, a Civil War hero (who lost an arm at Shiloh), and a passionate naturalist and geologist, in 1869 Powell tackled the vast and dangerous gorge carved by the Colorado River and known today (thanks to Powell) as the Grand Canyon." Powell was a scientist, bureaucrat, and land-management pioneer. "He began a national conversation about sustainable development when most everyone else still looked upon land as an inexhaustible resource. Though he supported irrigation and dams, his prescient warnings forecast the 1930s dust bowl and the growing water scarcities of today. Practical, yet visionary, Powell didn't have all the answers, but was first to ask the right questions.