Ontario is a city located in south west San Bernardino County, California, United States, 35 miles east of downtown Los Angeles. Located in the western part of the Inland Empire region, it lies just east of the Los Angeles county line and is part of the Greater Los Angeles Area. Wikipedia

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