Rubidoux (/ˈruːbɨdoʊ/ ROO-bə-doh) was a census-designated place and an unincorporated community in Riverside County, California. As of the 2010 census, the population was 34,280, up from 29,180 at the 2000 census. Like much of the fast-growing Inland Empire Metropolitan Area, Rubidoux is rapidly changing from a rural area of quarries and dairy farms to an exurb of Riverside. As of the 2000 Census, Rubidoux was the largest unincorporated community in the Inland Empire and in Riverside County.