Los Angeles County, California is 51 times larger than Riverside, California.
Area: 10,580 km2 calculated
Los Angeles County, also known as L.A. County, officially the County of Los Angeles, is a county in the U.S. state of California. As of the 2010 U.S. Census, the county has a population of 9,818,605, making it the most populous county in the United States. Wikipedia
Area: 208 km2 calculated
Riverside is a city in Riverside County, California, United States, located in the Inland Empire metropolitan area. Riverside is the county seat of the eponymous county and named for its location beside the Santa Ana River. Wikipedia