Riverside, city, seat (1893) of Riverside county, southern California, U.S. The city lies on the Santa Ana River. With San Bernardino and Ontario it forms a metropolitan complex east of Los Angeles. The city was laid out in 1870 in part on a section of Rancho Jurupa, a Mexican land grant of 1838. Initially named Jurupa, the city began as a silk-growing colony. Renamed Riverside, it developed as a citrus town; the state’s first Washington navel-orange trees, propagated from Brazilian cuttings, were cultivated there in 1873. The Parent Navel Orange Tree and the California Citrus State Historic Park are now popular local attractions.

Riverside’s economy includes manufacturing and distributive and educational activities. The Riverside campus (founded 1954) of the University of California has a citrus experiment station. A community college was established in Riverside in 1916, and the city is also the seat of La Sierra University (1922; Seventh-day Adventist) and California Baptist University (1950). The campus of Sherman Indian High School (1901), one of the many boarding schools operated by the U.S. government to encourage the assimilation of American Indians, includes one original building housing a museum that, among other things, preserves the school’s records. March Air Reserve Base (until 1996 March Air Force Base), with a field museum containing vintage aircraft, is nearby. At the northern edge of the city is the Santa Ana River Regional Park, and south of the city is Lake Mathews. Mount Rubidoux (1,399 feet [426 metres]) is a popular site for slab rock climbing. Other area recreational attractions include Lake Perris State Recreation Area, Mockingbird Canyon, and Sycamore Canyon Park. Inc. city, 1883. Pop. (2010) 303,871; Riverside–San Bernardino–Ontario Metro Area, 4,224,851; (2020) 314,998; Riverside–San Bernardino–Ontario Metro Area, 4,599,839.