The Forest Reserve Act of 1891 gave the President the authority to establish forest reserves in the U.S. Department of the Interior. After passage of the Transfer Act of 1905, forest reserves became part of the U.S. Department of Agriculture in the newly created U.S. Forest Service. Sawtooth National Forest was created as the Sawtooth Forest Reserve in the Department of Agriculture by proclamation of President Theodore Roosevelt on May 29, 1905. The forest's initial area was , and it was named after the Sawtooth Mountains in the northwestern part of the forest.