Mount Thielsen Wilderness is a protected area in Oregon’s southern Cascades, centered on Mount Thielsen and spanning parts of the Deschutes, Umpqua, and Fremont–Winema national forests. Established by Congress in 1984, it covers 55,100 acres and ranges from about 5,000 feet to the 9,182-foot summit of Mount Thielsen, a glacially shaped peak known as the “Lightning Rod of the Cascades.” Its landscape includes rolling hills, sharp ridges, changing forest zones, lakes such as Lucille and Maidu, and the headwaters of the Wild and Scenic North Umpqua River. With 78 miles of trails, including part of the Pacific Crest Trail, it is a notable destination for high-country recreation and scenery.