1900 - Edward S. Curtis exhibits his ethnological photographic studies of vanishing western Indian tribes.
1903 - President Roosevelt sets aside vast acres of federal land for protection of their natural and cultural features and creates the first national wildlife refuge at Florida’s Pelican Island.
1916 - President Woodrow Wilson signs the Organic Act, which establishes the National Park Service.
1924 - Ecologist Aldo Leopold achieves the designation of the first U.S. Forest Service wilderness area, the Gila Wilderness, in the Gila National Forest in New Mexico.
1935 - Forester Robert Marshall becomes principal founder of the Wilderness Society, leading the way for the modern American wilderness preservation movement.
1964 - The Wilderness Act is passed by Congress, creating the National Wilderness Preservation System.