Warren County is a county located in the U.S. state of New Jersey. As of the 2010 United States Census, the population was 108,692, having increased by 6,255 (+6.1%) from 102,437 counted at the 2000 Census, retaining its position as the 19th-most populous county in the state. Its county seat is Belvidere. It is part of the Allentown-Bethlehem-Easton, PA-NJ metropolitan area and is generally considered the eastern border of the Lehigh Valley, and also shares its western border with the New York City Metropolitan Area, with its northwestern section bordering The Poconos. The most populous place was Phillipsburg, with 14,950 residents at the time of the 2010 Census, while Hardwick Township, covered , the largest total area of any municipality.