Muncy showed promise of being a good copper district in the late 1870s and early 1880s. A post office opened in 1882 and in 1886 a city site named Defiance was laid out. Defiance was supposed to be a stop on the proposed Salt Lake and Los Angeles Railroad. However, by August the Defiance townsite was defunct. Muncy Creek’s fortunes fell during the mid-1890s and the post office closed on March 21, 1898. A small revival took place from 1908 to 1912 when the Cambria Copper Company reopened the mines. The company went bankrupt in early 1913 when the ore deposits gave out. Muncy Creek’s last revival began in 1919 and lasted until 1923 when the district returned to ranching.