In 1850, Mariposa County was the largest in area of the original 27 counties: It covered about a sixth of the state. It was larger than the present San Bernardino County, now largest in the country.  Mariposa County is the parent or grandparent of all or parts of twelve other counties, more  than was produced by any other California county. The county took its name from Mariposa Creek. The area was so named by Spanish explorers in 1807 when they discovered great clusters of butterflies ("mariposas" in Spanish) in the foothills of the Sierras. Some say these butterflies were really butterfly lilies. Territory which at one time was in  Mariposa County is now part or all of twelve other counties, Fresno, Inyo, Kern, Kings, Los Angeles, Madera, Merced, Mono, San Benito, San Bernardino, San Luis Obispo and Tulare counties.

.........