John Muir, born in Scotland in 1838 and raised in the United States, is one of history’s most revered and impactful environmentalists. Muir devoted his life to the preservation of wild places—he was sometimes called “John of the Mountains.” Through his popular writings and political activism, Muir had an extraordinary impact on the fate of public lands in America and on the very concept of environmental conservation worldwide. Muir founded the Sierra Club, with Henry Senger of the University of California, Berkeley, in 1892. Muir’s efforts to educate the public about the Yosemite wilderness and the threats to its ecosystem influenced Congress to establish Yosemite as a National Park in 1890, conserving the land for future generations. Many other wilderness areas were preserved thanks to Muir’s efforts, including Sequoia National Park. Muir died of pneumonia in California at 76. California celebrates John Muir Day on April 21st. Peaks, beaches, glaciers, camps, parks, and trails across America and in Scotland bear his name.