Pittsburgh International Airport opened on May 31, 1952, dedicated as Greater Pittsburgh Airport at a cost of $33 million. It was the largest commercial terminal in the United States at the time of opening. First flights began on June 3, 1952, and by 1953 the airport was handling over 1.4 million passengers annually. The airport was renamed Greater Pittsburgh International Airport in 1972 with the opening of its International Arrivals Building.

For decades, the airport's fortunes tracked those of its dominant carrier. From the 1960s to the mid-1980s, TWA operated a small hub at PIT. USAir, which itself evolved from Pittsburgh-rooted Allegheny Airlines, then built PIT into a major connecting hub, peaking at more than 500 daily flights and nearly 20 million annual passengers in the late 1990s. A $1 billion expansion in the early 1990s produced a landmark landside-airside design: a separate check-in terminal connected by an underground automated people mover to an X-shaped airside concourse. When it opened in October 1992, The New York Times called it the 'airport of the future.' US Airways dehubbed the airport in 2004, and passenger traffic dropped sharply.

PIT has since rebuilt on an origin-and-destination model, reaching nearly 10 million passengers in 2024, the highest total since 2006. No single carrier holds more than 30 percent market share, with Southwest, American, Delta, and United leading the field. The airport completed a $1.7 billion Terminal Modernization Program in November 2025, replacing the 1992 landside building with an 811,000-square-foot terminal that connects directly to the existing X-shaped airside concourses via a skybridge, eliminating the people mover. British Airways, Icelandair, and Aer Lingus, which launched nonstop Pittsburgh-Dublin service in May 2026, provide European connectivity. PIT sits roughly 20 miles west of downtown Pittsburgh in Findlay Township and Moon Township, covering 10,000 acres.