In the 1870s, hardrock miners who arrived in Animas Forks envisioned a modern mountain city with a telephone, telegraph, electric service, and a narrow gauge railroad, and by 1875 the community had established a post office as commercial, civic, and residential growth loomed. William W. Duncan came from Pennsylvania with his family at age 27, and in 1879 he and his wife Mary built this house, five years after the townsite was settled, for their growing family, including daughters Mary and Sarah and their infant son Willie Grant. The 1880 census recorded Duncan as a hardrock miner. The family brought with them East Coast architectural tastes, incorporating Victorian-era elements such as a finely detailed picturesque bay with tall windows for natural light and mountain views, features highly unusual in such a remote place at so early a date. The Duncans left Animas Forks in 1884, and the house remained as a statement of the optimism and confidence carried into the San Juan by a small number of prospectors and their families. Life above 11,000 feet was severe, with snowstorms up to 5 feet, prolonged sub-zero temperatures, and avalanches in the 1880s that isolated the community for months, demanding deep resilience and determination from families such as the Duncans. The Animas Forks townsite was listed on the National Register of Historic Places in 2011, and the Duncan House still retains many original features, including decorative trim and siding, the cedar shingle roof, and most original window and door hoods and casing. In 2014, during the 25th anniversary of the Alpine Loop Backcountry Byway designation, a major stabilization and restoration project preserved intact elements of the house and replicated many that had been lost or badly damaged. Preservation of Animas Forks buildings has been an ongoing struggle for 40 years, and the Duncan House likely would have been lost to weather and vandalism without volunteer efforts and partnerships involving the Bureau of Land Management and groups such as the San Juan County Historical Society.