Riverside County, California is one of fifty-eight counties in the U.S. state of California. As of the 2010 census, the population was 2,189,641, making it the 4th-most populous county in California and the 11th-most populous in the United States. The name was taken from the city of Riverside, which is the county seat.
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 and along the Interstate 10, 15, and 215 freeways.