Founded by legendary conservationist John Muir in 1892, the Sierra Club is now the nation's largest and most influential grassroots environmental organization -- with three million members and supporters. Successes range from protecting millions of acres of wilderness to helping pass the Clean Air Act, Clean Water Act, and Endangered Species Act. More recently, Sierra Club has made history by leading the charge to move away from the dirty fossil fuels that cause climate disruption and toward a clean energy economy.