John Muir (April 21, 1838 – December 24, 1914) was a Scottish-American naturalist, author, environmental philosopher 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 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 a prominent American conservation organization. The 211-mile (340 km) John Muir Trail, a hiking trail in the Sierra Nevada, was named in his honor. Other such places include Muir Woods National Monument, Muir Beach, John Muir College, Mount Muir, Camp Muir and Muir Glacier. In Scotland, the John Muir Way, a 130 mile long distance route, was named in honor of him.
California celebrates John Muir Day on April 21 each year. Muir was the first person honored with a California commemorative day when legislation signed in 1988 created John Muir Day, effective from 1989 onward. Muir is one of three people so honored in California, along with Harvey Milk Day and Ronald Reagan Day.