John Muir (21 April 1838 – 24 December 1914) was a Scottish-born American naturalist, author, and early advocate of preservation of wilderness in the United States. His letters, essays, and books telling of his adventures in nature, especially in the Sierra Nevada mountains of California, have been read by millions. His activism helped to preserve the Yosemite Valley, Sequoia National Park and other wilderness areas. The Sierra Club, which he founded, is now one of the most important conservation organizations in the United States. One of the most well-known hiking trails in the U.S., the 211-mile (340 km) John Muir Trail, was named in his honor. Other places named in his honor are Muir Woods National Monument, Muir Beach, John Muir College, Mount Muir, Camp Muir and Muir Glacier.