• City
  Roselle
• County
  Union
• State
  
• Population
  536,499

Union County is a county located in the U.S. state of New Jersey. At the 2010 United States Census, the population was 536,499, an increase of 13,958 (2.7%) from the 522,541 enumerated in the 2000 Census, making it the seventh-most populous county in the state, having been surpassed by Ocean County.[4][5] It is part of the New York metropolitan area. Its county seat is Elizabeth.[2][6] The Bureau of Economic Analysis ranked the county as having the 119th-highest per capita income of all 3,113 counties in the United States (and the eighth-highest in New Jersey) in 2009.[7] A study by Forbes.com determined that Union County pays the second-highest property taxes of all U.S. counties, based on 2007 data.[8] With a population density of 4,955 people per square mile (water excluded), Union County was the 15th-most densely populated county in America as of the 2010 Census, and third-densest in New Jersey, behind Hudson County (ranked 6th at 9,754) and Essex County