Alpine County is a county in the eastern part of the U.S. state of California located within the Sierra Nevada on the state border with Nevada. As of the 2020 census, the population was 1,204, making it California's least populous county. The county seat is Markleeville and the largest community is Alpine Village.
History
thumb|left|Woods Lake, situated in Alpine County
The Washoe people, a Great Basin tribe, inhabited the Sierra Nevada on the California–Nevada boundary, with the Hung A Lel Ti band populating the Diamond Valley including what would become Alpine County.
Kit Carson and John C. Frémont were among the first explorers to bring nationwide attention to the Sierra Nevada region in their winter 1844 expedition, though the first known westerners to actually explore the area were Jedediah Smith and Joseph R. Walker. Though gold spurred the infrastructural development of Alpine County, the Comstock Lode found near Virginia City, Nevada and the subsequent silver boom was what triggered Alpine County's growth, even attracting gold miners from neighboring Nevada. This prompted the formation on March 16, 1864, from parts of Amador County, Calaveras County, El Dorado County, Mono County and Tuolumne County. At its formation, it had a population numbering around 11,000. By 1868, however, the local silver mines had proven unfruitful of replicating the Nevada silver boom and the population fell to about 685 in the 1870 Census, a decline that would steadily continue through the 1950s. was designated the county seat following the discovery of silver nearby by Norwegian miners. Markleeville, established by Jacob Markley in 1861 as a 160-acre claim encompassing a bridge and toll station, became the new county seat in 1875. The three national forests (Eldorado, Humboldt–Toiyabe and Stanislaus) means 96% of the county is owned by the federal government,
Geography
According to the United States Census Bureau, the county has an area of , of which is land and (0.7%) is water. The federal government owns about 96% of Alpine County, the highest percentage in California, including three national forests: Eldorado (54,318 acres, or 7.81% of the 695,098-acre total), Stanislaus (119,805 acres, or 13.32% of the 899,427 acre-total) and Humboldt–Toiyabe (233,962 acres, or 3.72% of the 6,290,945 acre-total).
Adjacent counties
- El Dorado County – northwest
- Douglas County, Nevada – northeast
- Mono County – southeast
- Tuolumne County – south
- Calaveras County – southwest
- Amador County – west
National protected areas
- Eldorado National Forest (part)
- Stanislaus National Forest (part)
- Toiyabe National Forest (part)
Geology
Alpine County's geology is characterized by granitic intrusions, volcanic activity, and glacial sculpting. A significant portion of Alpine County is underlain by granitic rocks of the Sierra Nevada Batholith, a vast composite of plutonic rocks formed during the Mesozoic Era, that extends along the Sierra Nevada mountain range.
During the Miocene epoch, the region experienced extensive volcanic activity, leading to the deposition of andesitic lava flows, ash-flow tuffs, and volcanic breccias. These volcanic deposits are particularly evident along Monitor Pass and Ebbetts Pass. The Pleistocene epoch brought significant glaciation to Alpine County, carving out characteristic alpine landforms such as U-shaped valleys, cirques, and moraines. These glacial features are prominent in areas like the Mokelumne and Carson-Iceberg Wildernesses.