Mount Baker Wilderness is a wilderness area within the Mount Baker-Snoqualmie National Forest in the western Cascade Range of northern Washington state. Its eastern border is shared with the boundary of the Stephen Mather Wilderness and North Cascades National Park for a distance of 40 miles (65 kilometers). The wilderness extends from State Route 20 north to the Canada-US border. On the west, it is bounded by the foothills of the Puget Sound lowlands.