Pennsylvania native John Castner discovered rich coal deposits along Belt Creek in 1870, and within a few years he and Fort Benton trader T.C. Power opened a commercial coal mine near here. They sold coal to the Great Northern Railway, the Boston and Montana Refinery in Great Falls, and for domestic use in central Montana. Belt began to serve the mine and attracted men from throughout the United States and Europe to work side by side underground. In 1885, Castner and his wife, Mattie, one of Montana's early African-American businesswomen, established a stage station and hotel at this site on the Lewistown-Great Falls Road. When the mine's new owner, the Anaconda Copper Mining Company, expanded operations in 1894, Belt changed profoundly. Its commercial district moved to the area beside the stage station on what became known as Castner Street. By the early twentieth century, a jumble of wooden false-front commercial buildings and saloons lined the street, reflecting the community's origins as a mining camp. In the early 1900s, further mine expansion and the surrounding area's growing dependence on agriculture significantly changed the district's appearance. The old false-front buildings gave way to more substantial stone and brick-front buildings, which collectively conveyed the appearance of a prosperous and stable community. The district represents Belt's transformation from a mining camp into a modern city.