Muir's main goal was to draw attention to the devastation of mountain meadows and forests by sheep and cattle in the Yosemite Valley and California's Sierra Nevada. In 1890, Muir played a huge role in Congress establishing the Yosemite National Park. He also influenced the establishment of Sequoia, Mount Rainier, Petrified Forest, and Grand Canyon national parks. What he is most famous for is the creation of the Sierra Club.
He is considered to be the country's most famous and influential naturalist and conservationist. He taught the people of his time and ours the importance of experiencing and protecting our natural heritage.
John Muir's biography:
http://www.sierraclub.org/john_muir_exhibit/life/muir_biography.aspx
