7. JOHN MUIR: APRIL 21, 1838
After an industrial accident blinded him for six weeks, John Muir left his job behind and began a pilgrimage to explore the United States on foot. He set off in September of 1867 on a 1000-mile walk from Kentucky to Florida, studying plants along the way. Muir traveled light, and relied on the kindness of strangers for his sustenance. The diary of his two-month journey was published as A Thousand-Mile Walk to the Gulf. Muir continued his wandering, falling more and more in love with the natural world. He founded the Sierra Club in 1892, and lobbied to have the Yosemite area preserved as a national park. That was after he and President Teddy Roosevelt spent three days camping in the wilderness in 1903. Muir is credited with inspiring the president to form an entire system of national parks—earning him the nickname, the "Father of the National Parks."