Beaverhead–Deerlodge National Forest, the largest national forest in Montana, spans 3.36 million acres in nine sections across the southwest and was formed in 1996 by merging two forests first named by Theodore Roosevelt in 1908. Its history reflects both conservation and environmental damage, especially in the Big Hole watershed, where logging, smelter smoke, and erosion helped spur federal protection. The forest includes major mountain ranges, wilderness areas, historic mining country, and Lemhi Pass, where the Lewis and Clark Expedition in 1805 recognized there was no continuous water route across the continent. It also preserves extensive wildlife habitat, trails, campgrounds, and scenic access.