Trenton–Mercer Airport (IATA: TTN, ICAO: KTTN, FAA LID: TTN), sometimes also referred to as Trenton Mercer Airport, 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. Formerly known as Mercer County Airport, the airport serves one scheduled airline plus general and corporate aviation.