The county took its name from
Mariposa Creek, named by Spanish explorers in 1806 when they discovered a large cluster of
butterflies ( in Spanish) in the
foothills of the
Sierra Nevada. Each year on the first weekend in May, residents mark the annual arrival of migrating
monarch butterflies with a "Butterfly Days" festival and parade. At the time of
statehood in 1850, Mariposa County was the largest of the original 27 California counties by area, covering over or about one-fifth of the state. It became known as the "Mother of Counties" because its territory was ceded over time to eventually form all of present-day
Merced,
Madera,
Fresno,
Tulare,
Kings, and
Kern counties; and parts of present-day
San Benito,
Mono,
Inyo,
San Bernardino, and
Los Angeles counties. The county's original seat was a now-nonexistent hamlet known as
Agua Fria (Spanish for "cold water"), about west of present-day Mariposa on Agua Fria Road. The county seat then moved to
Mariposa in 1854, resulting in the construction of the
Mariposa County Courthouse, whose grounds occupy an entire block. The courthouse, fronted by Bullion Street with Jones Street to the rear and 9th and 10th Streets on either side, is depicted on the Mariposa County Seal.
Gold Rush Mariposa County lies at the southern end of California's
Mother Lode region. During the
California Gold Rush, large quantities of gold were found and extracted, first in local
stream beds and later in
hard-rock mines. One of the most notable beneficiaries was
John C. Frémont, explorer and 1856
Republican presidential candidate, for whom the local hospital and Charles Street (more commonly known as "Highway 140") are named. Jessie Street in Mariposa is named for Frémont's wife,
Jessie Benton Frémont, who accompanied her husband on extended visits to the area, though they never established permanent residence in the county. Many aspects of the area's mining history are depicted in exhibits at two local museums: the Mariposa History Museum in the town of Mariposa, and the
California Mining and Mineral Museum at the Mariposa Fairgrounds, southeast of Mariposa on
State Route 49. The
Coulterville Main Street Historic District, listed on the
National Register of Historic Places in 1982, preserves 24 Gold Rush-era buildings along the main street of
Coulterville. Two small gold mines in Mariposa County, the Mockingbird mine and the Colorado Quartz mine, intermittently produce world-class specimens of crystalline gold for
mineral collectors. "Specimens from these occurrences commonly have bright luster and rich color, with well-developed crystals in unusual and attractive arrangements." The best-known example is "The Dragon", on display at the
Houston Museum of Natural Science. Among the county's Gold Rush-era settlements,
Cat Town gave its name to the Cat Town Mining District, a gold-bearing area in the western Sierra Nevada foothills catalogued by the California Division of Mines and Geology. ==Geography==