Mariposa is one of the 58 counties in the state of California. It was created in 1850, making it one of the original counties of the state. As of the 2010 census the population was 18,251, up from 17,130 in 2000. The county seat and largest city is Mariposa.
The county has 1,462.79 square miles (3,788.6 km2) of area, of which 1,451.12 sq mi (3,758.4 km2) is land. It is bordered by Tuolumne County on the north, [[Madera County, California|Madera County] on the east and south, Stanislaus County on the west and Merced County on the northwest.