The Sawtooth Wilderness was originally designated the Sawtooth Primitive Area in 1937 before becoming part of the National Wilderness Preservation System in 1972 under the Wilderness Act. Although entirely managed by Sawtooth National Forest, only about a quarter (25.33 percent) of the Sawtooth Wilderness lies within the area Congressionally designated as Sawtooth National Forest, with the majority (69.13 percent) lying in Boise National Forest and a relatively small portion (5.54 percent) in Salmon-Challis National Forest. According to the United States Environmental Protection Agency, the Sawtooth Wilderness has some of the clearest air in the lower 48 states.