Helena National Forest is located in west-central Montana, in the United States. Covering 984,558 acres (3,984.36 km2), the forest is broken into several separate sections. The eastern regions are dominated by the Big Belt Mountains, and are the location of the Gates of the Mountains Wilderness, which remains much as it did when the Lewis and Clark Expedition passed through the region. The western sections have both the continental divide and the Scapegoat Wilderness area, which is part of the Bob Marshall Wilderness complex. The southern region includes the Elkhorn Mountains. The forest is composed of a mixture of grass and sagebrush covered lowlands with "island" pockets of lodgepole pine and more mountainous areas where Douglas fir, spruce and larch can be found. The rocky mountains in the region do not exceed 10,000 feet.

The Gates of the Mountains Wilderness is located in the U.S. state of Montana. Created by an act of Congress in 1964, the wilderness is managed by Helena National Forest. A day use campground near the Gates of the Mountains, Meriwether Picnic site, is named in honor of Meriwether Lewis.