Rubidoux was a census-designated place and unincorporated community in Riverside County, California, until July 1, 2011, when it became a neighborhood of the newly formed city of Jurupa Valley. The city is located within Southern California's Inland Empire region, which is part of the Greater Los Angeles Area. Along with the rest of Jurupa Valley, Rubiā¦Rubidoux was a census-designated place and unincorporated community in Riverside County, California, until July 1, 2011, when it became a neighborhood of the newly formed city of Jurupa Valley. The city is located within Southern California's Inland Empire region, which is part of the Greater Los Angeles Area. Along with the rest of Jurupa Valley, Rubidoux has transformed from a rural area of quarries and dairy farms, in mid to late 20th century, to a suburb of the two larger regions. As of the 2010 census, the population was 34,280, up from 29,180 at the 2000 census.