Union County, New Jersey

Union County
Downtown Westfield in July 2005
Location within the U.S. state of New Jersey
New Jersey's location within the U.S.
Coordinates: 40°39′N 74°17′W / 40.65°N 74.29°W / 40.65; -74.29
Country United States
State New Jersey
Founded1857
Named afterUnion threatened by slavery dispute
SeatElizabeth
Largest cityElizabeth (population and area)
Government
  Commission ChairSergio Granados (D, term ends December 31, 2025)
Area
  Total
105.41 sq mi (273.0 km2)
  Land102.77 sq mi (266.2 km2)
  Water2.64 sq mi (6.8 km2)  2.5%
Population
 (2020)
  Total
575,345
  Estimate 
(2024)
594,160
  Density5,500/sq mi (2,100/km2)
Time zoneUTC−5 (Eastern)
  Summer (DST)UTC−4 (EDT)
Congressional districts7th, 8th, 10th, 12th
Websitewww.ucnj.org

Union County is a county in the northern part of the U.S. state of New Jersey. As of the 2020 United States census, the county was the state's seventh-most-populous county with a population of 575,345, its highest decennial count ever and an increase of 38,846 (+7.2%) from the 2010 census count of 536,499. Its county seat is Elizabeth, which is also the most populous municipality in the county, with a 2020 census population of 137,298, and the largest by area, covering 13.46 square miles (34.9 km2). The county serves as a transition point between the Central Jersey and North Jersey regions of the state.

In 2015, the county had a per capita personal income of $60,089, the seventh-highest in New Jersey and ranked 152nd of 3,113 counties in the United States. 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. A study by Forbes.com determined that Union County residents pay the second-highest property taxes of all U.S. counties, based on 2007 data.

With a population density of 4,955 inhabitants per square mile (1,913/km2) in 2000, Union County was the 15th-most densely populated county in the United States as of the 2010 Census, and third-densest in New Jersey, behind Hudson County (ranked 6th nationwide at 9,754 per square mile) and Essex County (ranked 11th at 6,126).