Ewing Township is a township in Mercer County, New Jersey, United States. The township is within the New York metropolitan area as defined by the United States Census Bureau. It also directly borders the Philadelphia metropolitan area and is part of the Federal Communications Commission's Philadelphia Designated Market Area. As of the 2010 United States Census, the township's population was 35,790, reflecting an increase of 83 (+0.2%) from the 35,707 counted in the 2000 Census, which had increased by 1,522 (+4.5%) from the 34,185 counted in the 1990 Census.
The earliest inhabitants of present-day Ewing Township in the historic era were Lenni Lenape Native Americans, who lived along the banks of the Delaware River. Their pre-colonial subsistence activities in the area included hunting, fishing, pottery-making, and simple farming. European settlers, mostly from the British Isles, began to colonize the area in 1699. One of the earliest European settlers was William Green, and his 1717 farmhouse still stands on the campus of The College of New Jersey.
The area that is now Ewing Township was part of Hopewell Township in what was a very large Burlington County at the beginning of the 18th century. In 1714 Hopewell was removed from Burlington County and added to Hunterdon County. By 1719, the area which was to become Ewing Township had been removed from Hopewell Township and added to the newly created Trenton Township. Portions of Trenton Township were incorporated as Ewing Township by an act of the New Jersey Legislature on February 22, 1834, posthumously honoring Charles Ewing for his work as Chief Justice of the New Jersey Supreme Court.