About Riverside County

Riverside County is one of 58 counties in the U.S. state of California. The name was taken from the city of Riverside, which is the county seat. Rectangle-shaped, Riverside County covers 7,208 square miles (18,670 km2) in Southern California. Riverside County lies inland of Los Angeles County and is bordered on the west by Orange County; on the east by La Paz County, Arizona; on the southwest by San Diego County; on the southeast by Imperial County; and on the north by San Bernardino County. Together, Riverside and San Bernardino Counties have been dubbed the Inland Empire.

The population of Riverside County was 2,189,641 in 2010. It is the fourth-most populous county in California and among the fastest-growing areas of the United States in the past fifty years (since 1960). There is a high concentration of sprawling house tract communities around Riverside and along the Interstate 10, 15, and 215 freeways.

Geographically, the county is mostly desert in the central and eastern portions of the county and is a Mediterranean climate in the western portion of the county. Most of Joshua Tree National Park is located in the county.

The indigenous peoples of what is now Riverside County are the Luiseño, Cupeño and Cahuilla Indians. When the initial 27 California counties were established in 1850 the area today known as Riverside County was divided between Los Angeles County and San Diego County. In 1853 the eastern part of Los Angeles County was used to create San Bernardino County. Between 1891 and 1893 several proposals, and legislative attempts, were put forth to form new counties in Southern California. These proposals included one for a Pomona County and one for a San Jacinto County. None of the proposals were adopted until a measure to create Riverside County was signed by Governor Henry H. Markham on March 11, 1893.

The new county was created from parts of San Bernardino County and San Diego County. On May 2, 1893, seventy percent of voters approved the formation of Riverside County. Voters chose the city of Riverside as the county seat, also by a large margin. Riverside County was officially formed on May 9, 1893, when the Board of Commissioners filed the final canvas of the votes.

According to the 2000 census, the county has a total area of 7,303.13 square miles (18,915.0 km2), of which 7,207.37 square miles (18,667.0 km2) (or 98.69%) is land and 95.76 square miles (248.0 km2) (or 1.31%) is water. At roughly 180 miles (290 km) wide in the east-west dimension, the area of the county is massive. Riverside County, California is roughly the size of the State of New Jersey in total area. County government documents frequently cite the Colorado River town of Blythe as being a "three-hour drive" from the county seat, Riverside. Some view the areas west of San Gorgonio Pass as the Inland Empire portion of the county and the eastern part as either the Mojave Desert or Colorado Desert portion. There are probably at least three geomorphic provinces: the Inland Empire western portion, the Santa Rosa Mountains communities such as Reinhardt Canyon, and the desert region. Other possible subdivisions include tribal lands, the Colorado River communities, and the Salton Sea.