Montréal–Trudeau International Airport (YUL) opened on September 1, 1941, on the site of a former racetrack in Dorval, Quebec, replacing Saint-Hubert Airport, which had served the city since 1927. Built to support the British Commonwealth Air Training Plan during the Second World War, it transitioned to civilian use and by the 1950s was Canada's busiest airport and its principal transatlantic gateway.

The airport's most significant early milestone came on December 15, 1960, when Canada's Minister of Transport inaugurated a new $30 million terminal, at the time the largest single airport terminal building in the world. The facility was designed to handle the new generation of jet aircraft, with Trans-Canada Air Lines operating DC-8s out of the airport by 1960. That same year, the airport was formally renamed Montréal–Dorval International Airport. The next two decades brought turbulence: from 1975 to 1997, the federal government required all international flights (except US services) to operate from the newly built Mirabel Airport, approximately 40 kilometres northwest of the city. Dorval retained domestic and transborder routes, but the split operation drove airlines toward Toronto and eroded Montreal's network standing.

In 1997, international flights returned to Dorval, and a CAD 716 million expansion program launched in 2000 rebuilt the terminal for a new era. The airport was renamed in honour of former Prime Minister Pierre Elliott Trudeau in 2004. Today, operated by Aéroports de Montréal under a long-term lease from Transport Canada, it recorded a record 22.4 million passengers in 2024, making it the busiest airport in Québec and third-busiest in Canada. The single integrated terminal is divided into domestic, US transborder, and international jetties, with US Customs and Border Protection preclearance on site. Air Canada maintains its eastern Canada hub here, while Air Transat, WestJet, Porter Airlines, and dozens of international carriers connect the airport to five continents. A direct REM light-rail station connected to the terminal is under construction, expected to open around 2027.