pastures in August and September. By the 1890s, the area was getting overgrazed. Despite regulatory measures, sheep grazing peaked in 1910 before being banned in the 1930s at North and Middle Sister, and in 1940 at South Sister. In 1892, President Grover Cleveland decided to create the Cascades Forest Reserve, based on the authority of the Forest Reserve Act of 1891. Cascades Reserve was a strip of land from wide around the main crest of the Cascade Range, stretching from the Columbia River almost to the border with California. In 1905, administration of the Reserve was moved from the General Land Office to the United States Forest Service. The Reserve was renamed the Cascade National Forest in 1907. In 1908, the forest was split: the eastern half became the Deschutes National Forest, while the western half merged in 1934 to form the Willamette National Forest. Most of the Three Sisters glaciers were described for the first time by Ira A. Williams in 1916. Collier Glacier, between North and Middle Sister, was first studied and mapped by Edwin Hodge. Ruth Hopsen Keen took a forty-year photographic record of Collier Glacier, documenting part of the retreat of the glacier from 1910 to 1994. In the 1930s, the Three Sisters were part of a proposed National Monument. To maintain its authority over the region, the Forest Service decided to create a primitive area in 1937. The following year, at the instigation of Forest Service employee Bob Marshall, it was expanded by in the French Pete Creek basin. In 1957, the Forest Service decided to reclassify the area as a wilderness area and removed the old-growth forest of the French Pete Creek basin, despite protests of local environmental activists. The area became part of the National Wilderness Preservation System when the Wilderness Act of 1964 was passed, but the area still excluded the French Pete Creek basin. Responding to environmental mobilization throughout the state of Oregon, Congress passed the Endangered American Wilderness Act of 1978, which led to the reinstatement of French Pete Creek and its surroundings in the Three Sisters Wilderness Area. The Oregon Wilderness Act of 1984 further expanded the wilderness with the addition of around Erma Bell Lakes. Recreation The Three Sisters are a popular climbing destination for hikers and mountaineers. Due to extensive erosion and rockfall, North Sister is the most dangerous climb of the three peaks, and is often