20th century

Lehigh Valley International Airport opened in 1929. Scheduled airline flights began on September 16, 1935, with flights by United Airlines' Boeing 247s. The airport hangar initially served as the passenger terminal. The first terminal building at the airport was built in 1938 as part of a Works Progress Administration project.

World War II

During World War II, the U.S. Navy's V-5 flight training program was conducted at the airport in conjunction with ground training held at nearby Muhlenberg College. The headquarters of Group 312 of the Civil Air Patrol was based at the airport. One of its activities was to provide a courier service for cargo defense plants. Allentown-based pilots patrolled the Atlantic coastline during World War II and were active in recruiting young men for the U.S. Air Force's air cadet program.

In January 1944, work on a new runway was completed, and a Class A U.S. Weather Bureau station also was installed. About 1,000 Naval Aviation Cadets were trained in 1943, and civil and military air traffic both increased.

In late July 1944, the War Production Board approved the construction of a second-story addition to the airport's administration building. The building housed the Lehigh Aircraft Company, the weather bureau station, the Civil Aeronautic communications station, and the office and waiting room of United Airlines. In August, the V-5 flight training program ended when the Navy decided to move all flight training to naval air bases under Navy pilots.

Expansion

In April 1946, the Lehigh Airport Authority was created to own and manage the airport. The October 1946 command and general staff diagram shows four runways forming an asterisk: runway 1 was 2680 feet long, runway 6 was 4000 feet, runway 9 was 3800 feet and runway 14 was 3100 feet.

Construction began on the present terminal in 1973. The project, designed by Wallace & Watson, was completed in 1976.

Construction on a new passenger terminal began in 1948 and was finished in 1950. Allentown–Bethlehem–Easton (ABE) Airport, as it was then called, had flights on United and TWA since 1947, and Colonial Airlines since 1949. Douglas DC-4s and DC-6s appeared after runway 6 was extended to 5,000 feet. TWA left in 1967, replaced by Allegheny Airlines; Colonial's successor Eastern Air Lines remained until 1991. Republic Airlines' McDonnell Douglas DC-9's offered nonstop flights to Detroit and were continued by Northwest Airlines after Northwest's acquisition of Republic. Northwest also offered one-stop flights to Detroit with a stop in Harrisburg.

21st century

Regional partners replaced the successor Northwest around 2003. Delta Air Lines started nonstop flights to Atlanta and Harrisburg in 1991 and later added flights to Cincinnati, initially operated by Delta until changing to Delta Connection carrier Comair.

In 2012, Frontier Airlines started twice-a-week nonstop Airbus A319 flights to Orlando International Airport; they ended in 2013. Allegiant Air now flies nonstop from Lehigh Valley to Orlando via Orlando Sanford International Airport (SFB) in nearby Sanford, Florida.

In 2009 and 2010, the most recent terminal renovations were completed in two phases:

Phase I (April 2009). Cost: $7,253,235; PENNDOT grant amount: $3 million; general contractor: Lobar, Inc. (Dillsburg, Pennsylvania); architect: Breslin, Ridyard, Fadero Architects (Allentown); square footage of the Phase I project: 24,000 sq.ft., 7,000 sq.ft. of which is new space.

Phase II (November 2010). Cost: about $7,225,000; PENNDOT grant amount: $3.5 million; general contractor: E.R. Stuebner Construction, Inc. (Reading); architect: Breslin, Ridyard, Fadero Architects (Allentown); square footage of renovated space: 33,600 sq.ft.

On May 26, 2016, Solar Impulse 2 (SI2), piloted by Bertrand Piccard, completed the 13th leg from Dayton, Ohio of the first around the world (43,041 km) fuel-less flight by this solar-powered plane with a landing at ABE. On June 11, 2016, André Borschberg began the 14th leg (ABE to JFK, which included a dramatic Statue of Liberty flyover). While at ABE, an open house was held for public viewing of the SI2 aircraft.

The Federal Aviation Administration (FAA) National Plan of Integrated Airport Systems for 2023–2027 categorizes Lehigh Valley International Airport as a small hub primary commercial service facility. In 2019 to 2023, the FAA categorized the airport as a "non-hub primary" and previous years it was categorized as a "small hub."

After several years of falling passenger counts in the early 2000s, the airport has lately experienced a significant rebound in passenger totals due to it being an alternative to the comparatively congested Philadelphia International and Newark Liberty International airports, its facility improvements, a rapidly growing regional population, carrier expansions, especially Allegiant Air, and multiple new routes being added for popular destinations and major hubs across the country.

In 2019, the airport was utilized by 911,970 passengers, which represented an increase of 15.01% over its use the previous year, in 2018.