Origins

In 1923, a landing field was established east of Central Avenue (3 mi (4.8 km) west of the current airport) on land leased from the Union Pacific Railroad. The airfield was named Latimer Field after an orange-packing company next to the airstrip. An airport was built there by one of the first flying clubs in Southern California, the Friends of Ontario Airport. In 1929, the city of Ontario purchased 30 acres (12 ha), now in the southwest corner of the airport, for $12,000 (equivalent to $225,000 in 2025), and established the Ontario Municipal Airport.

In 1941, the city bought 470 acres (190 ha) around the airport and approved construction of new runways, which were completed by 1942, with funds from the Works Progress Administration. The 6,200 ft (1,900 m) east–west runway and the 4,700 ft (1,400 m) northeast–southwest runway cost $350,000 (equivalent to $6,900,000 in 2025). On 27 February 1942, an Army Air Corps plane made the first landing at the new airport. By 1943, the airport was an Army Air Corps Lockheed P-38 Lightning training base and North American P-51 Mustang operating base.

After the war, it was one of the five large storage, sales, and scrapping centers for United States Army Air Forces aircraft established by the Reconstruction Finance Corporation; others were at Albuquerque AAF, New Mexico; Altus AAF, Oklahoma; Kingman AAF, Arizona; and Walnut Ridge AAF, Arkansas.

Ontario International Airport

In late 1945, a new airline called Industrial Air Transport selected Ontario as its headquarters. Industrial was founded by former pilots of Consairway, a World War II division of Convair that pioneered transPacific flights on behalf of the Air Transport Command (ATC). At that time, Ontario's airport had the best runways in the LA area for supporting long-haul air transport. Industrial's plans accelerated when, in March 1946, it was awarded a contract to fly 15 Douglas C-54 (DC-4) aircraft for the Air Transport Command to fly across the Pacific to Japan. In early April, soon after starting service for the ATC, Industrial changed its name to Pacific Overseas Airlines (POA). Shortly thereafter, Ontario changed the name of the airport to Ontario International Airport. The airport and city greatly accommodated POA, including buying two war-surplus steel hangars on behalf of the airline. Later in the year POA started flying its own C-54 aircraft from Ontario to Shanghai and Manila, making Ontario an Asian gateway: ambassadors and other Asian VIPs entered and departed the US through Ontario. By the end of the year, POA had 19 C-54 aircraft and over 700 employees. In 1947, POA entered into a joint-venture with shareholders from what was then called Siam to create Pacific Overseas Airlines (Siam) (POAS). POAS started scheduled service from Bangkok to Ontario. External links has very brief color footage of Pacific Overseas Airlines at Ontario in 1947.

However, POA's fall was almost as swift as its rise and by 1948 it had ceased airline operations, lingering at Ontario until 1952 as a maintenance provider. But POAS became a constituent airline that ultimately created today's Thai Airways International, making POA a Southern California ancestor of the Thai flag carrier.

In 1949, Western Airlines began scheduled flights; in 1955, Bonanza Air Lines flights started. Western and Bonanza nonstops did not reach beyond Las Vegas. In 1962, Western began nonstop flights to San Francisco (one Electra daily). In 1967, Bonanza began nonstop F27 flights to Phoenix.

Ontario and Los Angeles entered into a joint-powers agreement, making Ontario International Airport part of the Los Angeles regional airports system in 1967. In 1968, the airport had its first scheduled jet flights. In 1969, Continental Airlines started Boeing 720B nonstops to Denver and Chicago; Air California started Boeing 737 flights to San Jose; Pacific Southwest Airlines started San Francisco flights; and Western began 737 nonstops to Sacramento and Salt Lake City. In 1970, United Airlines started a nonstop to Chicago and American started flights to Dallas (and Chicago, for a short time). In September 1986, Ontario hosted the Concorde supersonic airliner during a promotional round-the-world flight.

In 1981, a second east–west runway, 26L/8R, was built, necessitating the removal of the old NE-SW runway 3/21. Remnants of the 3/21 runway are visible in the present-day taxiways. With the completion of the new runway, the existing runway 25/7 became 26R/8L. In 1985, the city of Los Angeles acquired Ontario International Airport outright from the city of Ontario. In 1987, Runway 26R/8L was extended to the east to bring the two runway thresholds side by side, so aircraft would be higher over neighborhoods. 26R/8L became the main departing runway and 26L/8R the main arrival runway.

For a number of years, the airport operated alongside Ontario Air National Guard Station, which was closed as a result of the 1995 Base Realignment and Closure Commission.

In 1998, the new and larger airport terminal opened, designed by DMJM Aviation.