[2][5] It is the West Coast air and truck hub for UPS Airlines and is a major distribution point for FedEx Express.

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.

On 17 May 1946, two Army surplus steel hangars arrived at the airport, which the Ontario city council had authorized the $50,000 purchase of just the previous week.

Thought to be the only pair available in the U.S., City Manager Harold J. Martin observed that even if they could be acquired at a later date, the cost would be several times that afforded by prompt action.

[10] A Pacific Overseas Airlines flight from Shanghai arrived at Ontario on 18 May 1946, "which inaugurated regular round-trip air passenger service between the United States and the Orient.

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.

The "LA" portion was added to remind fliers of Greater Los Angeles and to avoid confusion with the province of Ontario in Canada.

Around the time of the 2008 financial crisis, JetBlue suspended service to ONT, and major legacy carriers significantly decreased their passenger volume at the airport.

The surrounding Inland Empire region was hit hard by the financial crisis, with the nearby city of San Bernardino declaring bankruptcy.

Wapner argued that the City of Los Angeles had no interest in maintaining service at an airport well beyond its borders.

[23] Local groups then sued the city of Los Angeles, a suit that was temporarily suspended when both sides agreed to attempt to work together.

[26] On September 30, 2017, it was announced that China Airlines would begin nonstop flights from Ontario to Taipei, which started in spring 2018.

On January 1, 2024, they ended flights to Las Vegas and subsequently discontinued all scheduled service altogether.

On the east end is a ground transportation center that consolidates the rental car companies in one central location.

The Omnitrans 61 bus traverses the airport, providing connections to each of the terminals, rental car and remote parking lots, and public transit stops.

This procedure is similar to the one employed by LAX, where all landings are conducted from the east and all takeoffs are to the west (known as "over-ocean" operations) between 00:00 and 06:30.

Omnitrans, San Bernardino County's main public transportation agency, operates three routes near the airport.

[37] Route 380, also called ONT Connect, provides non-stop daily service every 35 to 60 minutes between the airport and Rancho Cucamonga station,[38] where passengers can connect to Metrolink's San Bernardino Line, which operates daily with service to Los Angeles Union Station.

[40] Initially, The Boring Company proposed constructing a single 2.8-mile (4.5 km) tunnel similar to the Las Vegas Convention Center Loop that would cost $60 million.