Abstract John Muir has long been known as a significant figure in the history of conservation, including for promoting the recognition of the Yosemite Valley in the Sierra Nevada Mountains of California as a national park by the American people and government. Muir is known particularly for his pivotal involvement in the establishment of the Sierra Club, one of North America’s leading conservation associations. His place in the history of biogeography has been largely unrecognized, although a reading of his books shows that there is a rich seam of innovative historical and ecological biogeographical ideas resulting from his many years living in the Sierras. Added to Muir’s interests in the Sierra Mountains and the Sierra Club were his explorations of the mountain ranges and forests of Alaska, as well as his near world-wide travels to Europe, Asia, Africa, South America and the Pacific. The literature on biogeography has remained very largely isolated from Muir’s writing, a dissociation that the present paper seeks to remedy.