Copperopolis, originally known as Copper Canyon and locally called “Copper,” was established in 1860 after copper was discovered there and grew into a thriving Civil War-era mining town that became the second largest copper producing area in the U.S., supplying much of the copper used by the Union Army. As Mother Lode gold mines declined and the nation entered civil war, ore from Copperopolis was hauled by wagon to Stockton, sent by riverboat to San Francisco, and then shipped around the Horn to New York, Boston, and Wales for smelting and processing; later, in the early 1900s, the Calaveras Copper Co. built a smelter and used a 4,000-foot electric tram to carry raw ore and return waste rock, creating the mine tailings still visible behind buildings on the west side of Main Street. The U.S. Bureau of Mines credited the Copperopolis mines with producing 72,598,883 pounds of copper between 1861 and 1946, and mining booms in the 1860s, 1888, and 1909 to 1930 shaped a town that rapidly filled with homes, hotels, saloons, stables, rooming houses, racetracks, schools, churches, and businesses, with more than 4,000 residents at its height and many people working directly or indirectly for the mines. The town’s growth was tied to discoveries by Hiram Hughes, Thomas McCarty, William Reed, and Dr. Allen Blatchly, which led to the Union mine and other major mines along a two-mile claim parallel to Main Street, while prominent local institutions included the Union Mine Store, the Honigsberger Store, the 1864 Armory built for the Copperopolis Union Guard and 3rd California Infantry, the 1862 Old Corner Saloon, and the 1866 Congregational Church. Copperopolis was strongly pro-Union, so much so that it was nearly renamed “Union,” and it was the only town west of the Mississippi to house Union Guards during the Civil War because copper was vital for shells, bullets, munitions, and telegraph wire. The town’s later history included the Black Bart robbery near Funk Hill in 1875, freight traffic over Reeds Turnpike, the O’Byrnes Ferry bridge, the cemetery with its four walled sections, stonework by James Sykes, and surviving historic buildings and artifacts preserved by local residents after all copper mining ended by 1945.