The philosophy or policy that natural resources should be used cautiously and rationally so that they will remain available for future generations. Widespread and organized conservation movements, dedicated to preventing uncontrolled and irresponsible exploitation of forests, lands, wildlife, and water resources, first developed in the United States in the last decades of the nineteenth century. This was a time at which accelerating settlement and resource depletion made conservationist policies appealing both to a large portion of the public and to government leaders. Since then, international conservationist efforts, including work of the United Nations, have been responsible for monitoring natural resource use, setting up nature preserves, and controlling environmental destruction on both public and private lands around the world.

The name most often associated with the United States' early conservation movement is that of Gifford Pinchot, the first head of the U.S. Forest Service. A populist who fervently...