Riverside County, California is one of fifty-eight counties in the U.S. state of California. Riverside County is included in the Riverside-San Bernardino-Ontario, CA Metropolitan Statistical Area, also known as the Inland Empire. The county is also included in the Los Angeles-Long Beach, CA Combined Statistical Area. There is a high concentration of sprawling tract housing communities around Riverside. The name was taken from the city of Riverside, which is the county seat.
Roughly rectangle-shaped, Riverside County covers 7,208 square miles in Southern California, spanning from the Greater Los Angeles area to the Arizona border. 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. There is a diversity of flora and fauna within Riverside County. Vegetative plant associations feature many desert flora, but there are also forested areas within the county. There are 19 official wilderness areas in Riverside County that are part of the National Wilderness Preservation System.
The resort cities of Palm Springs, Palm Desert, Indian Wells, La Quinta, Rancho Mirage, and Desert Hot Springs are all located in the Coachella Valley region of Riverside County. Large numbers of Los Angeles area workers have moved to the county in recent years to take advantage of relatively affordable housing. Alongside neighboring San Bernardino County, it was one of the fastest growing regions in the state prior to the recent changes in the regional economy. In addition, smaller, but significant, numbers of people have been moving into Southwest Riverside County from the San Diego-Tijuana metropolitan area. The cities of Temecula and Murrieta accounted for 20% of the increase in population of Riverside County between 2000 and 2007.