McDonald Glacier is a small alpine glacier in Montana’s Mission Mountains, immediately north of McDonald Peak. Resting in a cirque below the peak at about 8,600 feet above sea level, it covers roughly 45 acres. Rather than a broad icefield, it is a compact high-mountain ice body shaped by the steep basin beneath McDonald Peak. Its secluded setting gives it the character of a remote mountain glacier, and it stands out today as one of the small remaining glaciers of the American West.