Riverside is one of the 58 counties in the state of California. It was created on May 9, 1893 from parts of San Bernardino and San Diego counties. Along with Kings and Madera counties, Riverside is the second youngest county in California. As of the 2010 census, the population was 2,189,641, up substantially from 1,545,387 in 2000.
The county seat and largest city is Riverside. Riverside measures 7,303.13 square miles (18,915.0 km2), of which 7,207.37 sq mi (18,667.0 km2) is dry land. It is bordered on the south by Imperial and San Diego counties, on the west by Orange County, on the north by San Bernardino County, and on the east by La Paz County, Arizona.