Atlantic County is a county located in the U.S. state of New Jersey. As of the 2010 United States Census, the county had a population of 274,549, having increased by 21,997 from the 252,552 counted at the 2000 Census (+8.7%, tied for third-fastest in the state), retaining its position as the 15th-most populous county in the state. As of the 2015 Census estimate, the county's population was 274,219, a decline of 0.2% from the 2010 enumeration. Its county seat is Mays Landing. The most populous place was Egg Harbor Township, with 43,323 residents at the time of the 2010 Census, while Galloway Township, covered 115.21 square miles (298.4 km2), the largest total area of any municipality, though Hamilton Township has the largest land area, covering 111.13 square miles (287.8 km2).