Ontario is a city in southwestern San Bernardino County, California, 35 miles (56 km) east of downtown Los Angeles and 23 miles (37 km) west of downtown San Bernardino, the county seat. Located in the western part of the Inland Empire metropolitan area, it lies just east of Los Angeles County and is part of the Greater Los Angeles Area. As of the 2010 Census, the city had a population of 163,924, up from 158,007 at the 2000 census.
The city is home to the Ontario International Airport, which is the 15th-busiest airport in the United States by cargo carried. Ontario handles the mass of freight traffic between the ports of Los Angeles and Long Beach and the rest of the country.It takes its name from the Ontario Model Colony development established in 1882 by the Canadian engineer George Chaffey and his brothers William Chaffey and Charles Chaffey. They named the settlement after their home province of Ontario.