Calaveras County, officially the County of Calaveras, is a county in the northern portion of the U.S. state, California. As of the 2010 census, the population was 40,171. The county seat is San Andreas. Angels Camp is the only incorporated city in the county. Calaveras is the Spanish word for skulls; the county was reportedly named for the remains of Native Americans discovered by the Spanish explorer Captain Gabriel Moraga.