Essex County is a county in the northeastern part of the U.S. state of New Jersey. As of the 2018 Census estimate, the county's population was 799,767, making it the state's third-most populous county, an increase of 3.1% from the 2010 United States Census, when its population was enumerated at 783,969, in turn, a decrease of 1.2% (9,664 fewer residents) from the 793,633 enumerated in the 2000 census. In 2010, the county dropped down to third-largest, behind Middlesex County, and was one of only two counties in the state to see a decline between 2000 and 2010 (Cape May County being the other). Its county seat is Newark, the most populous city in the state. It is part of the New York Metropolitan Area.