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.
Juan Bautista de Anza is said to have passed through the area on his 1774 expedition, and to this day a city park and a middle school bear his name. Following the 1819 establishment of San Bernardino Asistencia, which may have served as an outpost of the San Gabriel mission, it became part of a large, vaguely identified area called "San Antonio".
In 1826, Jedediah Smith passed through what is now Upland on the first overland journey to the West coast of North America via the National Old Trails Road (present-day Foothill Blvd).
The 1834 secularization of California land holdings resulted in the land's transferral to private hands. In 1881, the Chaffey brothers, George and William, purchased the land (which at that time also included the present-day city of Upland) and the water rights to it. They engineered a drainage system channeling water from the foothills of Mount San Antonio (colloquially known as "Mount Baldy") down to the flatter lands below that performed the dual functions of allowing farmers to water their crops and preventing the floods that periodically afflict them.