San Bernardino County, officially the County of San Bernardino, is a county located in the southern portion of the U.S. state of California. As of the 2010 U.S. Census, the population was 2,035,210, up from 1,709,434 in the 2000 census. With an area of 20,105 square miles, San Bernardino County is the largest county in the United States by area. It is larger than each of the nine smallest states, larger than the four smallest states combined, and larger than 71 different sovereign nations. The Yukon-Koyukuk Census Area in Alaska is larger than San Bernadino County, but it is part of Alaska's unorganized borough and thus not a county.
Located in southeast California, the thinly populated deserts and mountains of this vast county stretch from where the bulk of the county population resides in two Census County Divisions, some 1,422,745 people as of the 2010 Census, covering the 450 square miles (1,166 km2) south of the San Bernardino Mountains in San Bernardino Valley, to the Nevada border and the Colorado River.
Spanish Missionaries from Mission San Gabriel Arcángel established a church at the village of Politania in 1810. Father Francisco Dumetz named the church after San Bernardino on May 20, 1810, feast day of St. Bernardino of Siena. The Franciscans also gave the name San Bernardino to the snowcapped peak in Southern California, in honor of the saint and it is from him that the county derives its name. In 1819, they established the San Bernardino de Sena Estancia, a mission farm in what is now Redlands.
Following Mexican independence from Spain in 1821, Mexican citizens were granted land grants to establish ranchos in the area of the county. Rancho Jurupa in 1838, Rancho Cucamonga and El Rincon in 1839, Rancho Santa Ana del Chino in 1841, Rancho San Bernardino in 1842 and Rancho Muscupiabe in 1844.
Following the purchase of Rancho San Bernardino, and the establishment of the town of San Bernardino in 1851 by Mormon colonists, San Bernardino County was formed in 1853 from parts of Los Angeles County. Some of the southern parts of the county's territory were given to Riverside County in 1893.