Union County is a county in the northern-central 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 countyTable1. New Jersey Counties and Most Populous Cities and Townships: 2020 and 2010 Censuses, New Jersey Department of Labor and Workforce Development. Accessed December 1, 2022. 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. The United States Census Bureau's Population Estimates Program estimated a 2025 population of 601,863, an increase of 26,518 (+4.6%) from the 2020 decennial census. Its county seat is Elizabeth,New Jersey County Map, New Jersey Department of State. Accessed December 22, 2022. which is also the most populous municipality in the county, with a 2020 census population of 137,298, and the largest by area, covering . The county is part of the Central Jersey region of the state."Regions: North, Central, South, Shore - Best of NJ", Best of NJ. Accessed January 13, 2024. "Central Jersey consists of Hunterdon, Mercer, Middlesex, Somerset, and Union County."Willis, David P. "'This is how wars start': Does Central Jersey include both Ocean and Union counties?", Asbury Park Press, February 20, 2023. Accessed March 31, 2024. "North Jersey is defined as Sussex, Warren, Morris, Passaic, Bergen, Essex and Hudson counties; South Jersey would be Burlington, Camden, Gloucester, Atlantic, Salem, Cumberland and Cape May counties. But for Central, things get a little tricky. It would include Hunterdon, Somerset, Union, Middlesex, Mercer, Monmouth, and Ocean counties.""Does Central NJ exist? State group says Union County belongs", Asbury Park Press, February 26, 2022. Accessed July 24, 2025.
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.250 Highest Per Capita Personal Incomes available for 3113 counties in the United States: 2015, New Jersey Department of Labor and Workforce Development. Accessed October 24, 2017.Local Area Personal Income: 2015 , Bureau of Economic Analysis. Accessed October 24, 2017. 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 2009.250 Highest Per Capita Personal Incomes of the 3113 Counties in the United States, 2009 , Bureau of Economic Analysis. Accessed April 9, 2012. 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.Woolsey, Matt. "In Depth: Who Pays America's Highest Property Taxes? 2. Union County, N.J.", Forbes, January 23, 2009. Accessed October 2, 2013.
With a population density of 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)."Census 2000 Data Rankings; A data rankings document focused on the Roanoke Valley and Alleghany Highlands region" , Roanoke Valley-Alleghany Regional Commission, p. 22. Accessed October 6, 2013.Staff. "Census 2010 data show population and diversity trends" , USA Today. Accessed October 2, 2013. Click on "Population per Square Mile" to sort counties nationwide by descending population density, which was calculated based on total land area (including water) and lists Union as 18th and Essex as 14th.
History Etymology Established in 1857 as the last county created in New Jersey, it was named after the Union threatened by slavery dispute during this period, which would erupt into civil war in 1861.
History All of present-day Union County was part of the Elizabethtown Tract, which was purchased in 1664, by English colonists from the Lenape Native Americans that lived in the area of present-day Elizabeth, New Jersey. Union County was formed on March 19, 1857, from portions of Essex County; it was the last of New Jersey's 21 counties to be established.Snyder, John P. The Story of New Jersey's Civil Boundaries: 1606–1968, Bureau of Geology and Topography; Trenton, New Jersey; 1969. p. 237. Accessed January 21, 2013.
Many historic places and structures are to be found in the county, including on the National Register of Historic Places listings in Union County, New Jersey.New Jersey and National Registers of Historic Places - Union County , New Jersey Department of Environmental Protection Historic Preservation Office, updated November 28, 2016. Accessed December 21, 2016.
In the fall, Union County holds its annual "Four Centuries in a Weekend" festival for the public, celebrating and touring historic buildings, museums and sites in the county.Staff. "'Four Centuries in a Weekend' program at Nitschke House celebrates New Orange/Kenilworth, A College Town", Suburban News, October 8, 2015. Accessed January 3, 2017.
Geography According to the U.S. Census Bureau, as of the 2020 Census, the county had a total area of , of which was land (97.5%) and was water (2.5%).2020 Census Gazetteer File for Counties in New Jersey, United States Census Bureau. Accessed April 1, 2023.
Much of Union County is relatively flat and low-lying. Only in the northwestern corner does any significant relief appear as the Watchung Mountains cross the county. It is there that highest elevations, two areas approximately above sea level, are found in Berkeley Heights.New Jersey County High Points, Peakbagger.com. Accessed October 5, 2013. The lowest elevation is sea level along the eastern shore at the Arthur Kill.
Rivers, lakes and streams Arthur Kill Rahway River Elizabeth River Nomahegan Brook Marshes Creek Morses Creek Peach Orchard Brook Robinson's Brook Robinson's Branch Reservoir
Climate and weather
In recent years, average temperatures in the county seat of Elizabeth have ranged from a low of in January to a high of in July, although a record low of was recorded in February 1934 and a record high of was recorded in July 1993. Average monthly precipitation ranged from in February to in July. In Berkeley Heights average monthly temperatures range from 29.4 °F in January to 74.7 °F in July. The climate in the county is hot-summer humid continental (Dfa) in the west and humid subtropical (Cfa) in the east. The hardiness zone is 7a west of the Garden State Parkway and 7b to the east.
Demographics
Union County is ethnically diverse. Berkeley Heights, Clark, Roselle Park, Cranford, Kenilworth, Linden, New Providence, Scotch Plains, Springfield, Summit, Union and Westfield have high percentages of Italian American residents. Elizabeth, Plainfield, Rahway, Roselle and Union all have large African American communities. Roselle Park has a notably large Indian American community, while Roselle Park, Roselle, Linden, Rahway, Plainfield and particularly Elizabeth have fast-growing Hispanic and Portuguese populations.
The county's Jewish population was 35,000 as of 2004, with notable communities located in Cranford, Elizabeth, Hillside, Linden, Scotch Plains, Springfield, Union, and Westfield.Union County, Jewish Virtual Library. Accessed November 24, 2014. "Union County, county in N.E. New Jersey. Of Union County's 532,000 residents (2004 census), about 35,000 were Jews. Major Jewish communities are in Elizabeth-Hillside, Westfield, Scotch Plains, Springfield, Union, Cranford, and Linden."
2020 census
As of the 2020 census, the county had a population of 575,345. The median age was 38.7 years. 23.4% of residents were under the age of 18 and 14.3% of residents were 65 years of age or older. For every 100 females there were 93.5 males, and for every 100 females age 18 and over there were 90.6 males age 18 and over.
The racial makeup of the county was 41.1% White, 20.4% Black or African American, 0.7% American Indian and Alaska Native, 5.6% Asian, <0.1% Native Hawaiian and Pacific Islander, 18.4% from some other race, and 13.8% from two or more races. Hispanic or Latino residents of any race comprised 34.0% of the population.
100.0% of residents lived in urban areas, while <0.1% lived in rural areas.
There were 200,372 households in the county, of which 37.0% had children under the age of 18 living in them. Of all households, 48.9% were married-couple households, 16.6% were households with a male householder and no spouse or partner present, and 28.5% were households with a female householder and no spouse or partner present. About 23.2% of all households were made up of individuals and 10.0% had someone living alone who was 65 years of age or older.
There were 209,908 housing units, of which 4.5% were vacant. Among occupied housing units, 56.4% were owner-occupied and 43.6% were renter-occupied. The homeowner vacancy rate was 1.4% and the rental vacancy rate was 4.0%.
Racial and ethnic composition +Union County, New Jersey – Racial and ethnic compositionRace / Ethnicity (NH = Non-Hispanic)Pop 1980Pop 1990Pop 2000Pop 2010 Pop 2020% 1980% 1990% 2000% 2010% 2020White alone (NH)375,032322,247283,345243,312211,24574.40%65.26%54.22%45.35%36.72%Black or African American alone (NH)79,97989,222104,926111,705112,26115.87%18.07%20.08%20.82%19.51%Native American or Alaska Native alone (NH)4666685475465520.09%0.14%0.10%0.10%0.10%Asian alone (NH)6,23813,16419,78924,49631,9631.24%2.67%3.79%4.57%5.56%Native Hawaiian or Pacific Islander alone (NH)x included in the Asian category in the 1980 Censusx included in the Asian category in the 1990 Census12110778xx0.02%0.02%0.01%Other race alone (NH)1,6237211,4622,2796,1900.32%0.15%0.28%0.42%1.08%Mixed race or Multiracial (NH)x not an option in the 1980 Censusx not an option in the 1990 Census9,3407,35017,537xx1.79%1.37%3.05%Hispanic or Latino (any race)40,75667,797103,011146,704195,5198.09%13.73%19.71%27.34%33.98%Total504,094493,819522,541536,499575,345 100.00%100.00%100.00%100.00%100.00%
Racial / Ethnic Profile of places in Union County, New Jersey Racial / Ethnic Profile of places in Union County, New Jersey (2020 Census)Following is a table of towns and census designated places in Union County, New Jersey. Data for the United States (with and without Puerto Rico), the state of New Jersey, and Union County itself have been included for comparison purposes. The majority racial/ethnic group is coded per the key below. Majority minority with no dominant groupMajority WhiteMajority BlackMajority HispanicMajority Asian