Trenton–Mercer Airport (IATA: TTN[4], ICAO: KTTN, FAA LID: TTN) is a county-owned, joint civil–military, public airport located four miles northwest of Trenton in the West Trenton section of Ewing Township, Mercer County, New Jersey.

[9] The Federal Aviation Administration (FAA) National Plan of Integrated Airport Systems for 2023–2027 categorized it as a non-hub primary commercial service facility.

[10] The first airplane landed at what is now Trenton–Mercer Airport in 1907, in what was then Alfred Reeder's farm field, just off of Bear Tavern Road in Ewing.

During World War II, the nearby General Motors Inland Fisher Guide Plant ceased producing civilian vehicles and began making Grumman TBF Avenger carrier-based torpedo bombers for the United States Navy.

[note 1] After the war, the navy reestablished a presence with the construction of Naval Air Warfare Center Trenton adjacent to the airport, which remained open until 1997.

[12] NJ Transit Route 608 bus stops on Sam Weinroth Road near the terminal for travel to SEPTA's West Trenton station for connections to SEPTA's West Trenton Line to Center City Philadelphia, Trenton Transit Center for connections to Amtrak, NJ Transit's Northeast Corridor Line to Newark/New York, River Line to Camden, SEPTA's Trenton Line to Center City Philadelphia, other NJ Transit bus routes to points in Mercer County, South Jersey, and Philadelphia, and SEPTA Suburban Bus Route 127 to Oxford Valley Mall in Langhorne, PA, and Hamilton station for connections to NJ Transit's Northeast Corridor Line to Newark & New York.

[14] For the 12-month period ending April 2, 2019, the airport had 112,513 aircraft operations, an average of 308 per day: 92% general aviation, 4% commercial, 4% air taxi, and <1% military.

[17] The airport is also home to the Twin Pine Composite Squadron (NER-NJ-092) of the New Jersey Wing of the Civil Air Patrol.

Sky Lounge has another location past security near Gate 1 that serves drinks and pre-packaged sandwiches and wraps.

On November 8, 2013, Mercer County opened a renovated terminal, including a new modular trailer baggage claim outside the terminal, restrooms in the gate area (there were previously no restrooms past security), and—in the area originally occupied by the baggage claim—additional passenger seating and a new gate.