Atlantic County is a county located along the Jersey Shore in the U.S. state of New Jersey. As of the 2020 census, the county was the state's 15th-most-populous county, with a population of 274,534, a drop of 15 from the 2010 census count of 274,549. Its county seat is the Mays Landing section of Hamilton Township. The county is part of the Jersey Shore region of the state.