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.
The county seat is San Bernardino. The county is considered part of the Inland Empire region.