Rail Road Flat is a Gold Rush era mining town that was settled by gold seekers in 1849. The town was named for a wooden track which conveyed ore cars with waste rock to and from the diggings. It was the site of an Indian council as well as the center of rich placer and quartz mining. Its largest producer was the Petticoat Mine.
The post office was established in 1857, and the Edwin Taylor store was built in 1867. The first stamp mill was built in 1866, and by 1872 five or six mills were operating. The town's population was decimated in 1880 by Black Fever. By the end of the century, only two stamp mills and one arrastra were still in operation. A water conveyance system, Clark Ditch, was constructed to supply water to the mines and carried water from the South Fork of the Mokelumne River over 55 miles. Part of Clark Ditch was purchased in the 1930s by the Calaveras Public Utilities District. In 1976 Clark Ditch was converted to pipe.
The historic marker at Rail Road Flat is located at the north east intersection of Rail Road (County Road 13) and Summit Level Roads, 0.5 miles west of the post office in Rail Road Flat. and 12.5 miles south of Pioneer.
Along with Mark Twain’s famous "The Celebrated Jumping Frog of Calaveras County" story that spun into an annual fair and Jumping Frog Jubilee, Calaveras County is rich with Gold Rush history and folklore. Remnants of the railroads and Hispanic culture add to the charm of the county located in the Sierra Nevada foothills. Calaveras Big Trees State Park, a preserve of Giant Sequoia trees, and the uncommon gold telluride mineral Calaverite was discovered in the county in 1861, and is named for it.
Calaveras is a Spanish word meaning "skull." The name was first given to the river because of the great quantities of human skulls found along the lower reaches of the river.
Calaveras County is famous for its lode and placer mines, and the largest gold nugget from the United States was taken from the Morgan Mine at Carson Hill in 1854, weighing 214 pounds. For many years it was the principal copper-producing county in California. Cement deposits from its vast limestone deposits has become one of the county's major industries in recent years.