Custer National Forest spans widely scattered units across south-central Montana and into northwestern South Dakota, joining western mountain country in the Greater Yellowstone Ecosystem with eastern pine uplands and grasslands. Established in 1907 as Otter National Forest and renamed in 1908, it later absorbed Sioux National Forest and part of Beartooth National Forest, creating its present form. Managed with Gallatin since 2014, it includes alpine terrain, part of the Absaroka-Beartooth Wilderness, and Montana’s highest peak, Granite Peak. The forest also preserves Native American burial grounds, pictographs, and petroglyphs, while supporting recreation, cattle grazing, and abundant wildlife, including an exceptional concentration of merlins.