Kern County comprises the Bakersfield, CA Metropolitan Statistical Area. The county spans the southern end of the Central Valley. Covering , it ranges west to the southern slope of the Coast Ranges, and east beyond the southern slope of the eastern Sierra Nevada into the Mojave Desert.
The county's economy is heavily linked to agriculture and to petroleum extraction. There is also a strong aviation, space, and military presence, such as Edwards Air Force Base, the China Lake Naval Air Weapons Station, and the Mojave Air and Space Port.
Kern County was the site of the Battle of San Emigdio, in March 1824, between the Chumash Indians of the Santa Barbara Mission who rebelled against the Mexican government's taking over mission property and ejecting the natives. This battle with Mexican forces from Monterey under the command of Carlos Carrillo took place at the canyon where San Emigdio Creek flows down San Emigdio Mountain and the Blue Ridge south of Bakersfield near today's Highway 166. It was a low-casualty encounter, with only four Indians killed, and no Mexicans; the surviving Indians were pacified and brought back to Santa Barbara in June 1824 after a pursuit and negotiation in which many were allowed to keep their arms for the return march over the mountains.
In the beginning, the area that became Kern County was dominated by mining in the mountains and in the desert. In 1855 an attempt to form a county in the area was made when the California legislature took the southeastern territory of Tulare County on the west of the Sierra Nevada Mountains for Buena Vista County, but it was never officially organized prior to 1859, when the time of the enabling legislation ran out. The south of Tulare County was later organized as Kern County in 1866, with additions from Los Angeles and San Bernardino Counties. Its first county seat was in the mining town of Havilah, in the mountains between Bakersfield and Tehachapi.
The flatlands were considered inhospitable and impassable at the time due to swamps, lakes, tule reeds and diseases such as malaria. This changed when settlers started draining lands for farming and constructing canals, most dug by hand by hired Chinese laborers. Within 10 years the valley surpassed the mining areas as the economic center of the county, and the county seat was moved as a result from Havilah to Bakersfield in 1874.
The county derives its name from the Kern River, which was named for Edward Kern, cartographer for General John C. Frémont's 1845 expedition, which crossed Walker Pass. The Kern River was originally named Rio Bravo de San Felipe by Father Francisco Garces when he explored the area in 1776.
On July 21, 1952, an earthquake with the epicenter about south of Bakersfield, measuring 7.3 on the Richter scale killed 12 people. In addition to the deaths, it was responsible for at least 18 injuries and more than $60 million in property damage. The main shock was felt over much of California and as far away as Phoenix, Arizona and Reno, Nevada.
Between 1983 and 1986, several ritual sex ring child abuse cases occurred in Kern County, resulting in numerous long prison sentences, all of which were overturned—some of them decades later, because the prosecutors had coerced false testimonies from the purported child victims. The details of these false accusations are covered extensively in the 2008 documentary Witch Hunt, narrated by Sean Penn.