[17][18] 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.

It is there that highest elevations, two areas approximately 560 feet (170 m) above sea level, are found in Berkeley Heights.

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.

[citation needed] 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.

[26] The 2010 United States census counted 536,499 people, 188,118 households, and 134,692 families in the county.

In their legislative role, they formulate and adopt a budget and set county policies and procedures.

These include committees on Economic Development, Parks and Recreation, and Public Works and Policy.

[51] In 2023, Union County agreed to honor the site in North Jersey of what local activists described as the public execution by burning at the stake of three enslaved New Jerseyans in 1741.

The logo depicted Hannah Caldwell being shot by a British light infantryman during the Battle of Connecticut Farms.

[61] In 2011, an investigation found mismanagement of county funds in association with MusicFest, a free annual concert.

[62] In 2009, following a First Amendment challenge by the American Civil Liberties Union, the county commissioners agreed to issue a public apology for cutting off speech by a resident who was addressing the board about possible nepotism on the county payroll.

[64][65] For the 119th United States Congress, New Jersey's 7th congressional district is represented by Thomas Kean Jr. (R, Westfield).

[67][68] For the 119th United States Congress, New Jersey's 10th congressional district is represented by LaMonica McIver (D, Newark).

[69] For the 119th United States Congress, New Jersey's 12th congressional district is represented by Bonnie Watson Coleman (D, Ewing Township).

Annette Quijano (D) Nancy Munoz (R) Linda S. Carter (D) Cleopatra Tucker (D) The Union County Sheriff's Office is located in Elizabeth, New Jersey.

It was headed by Ralph Froehlich, a Union resident who was first elected in 1977 and served in office for 37 years, making him the longest-serving Sheriff in New Jersey history.

The Union County Police Department operates independently of the Sheriff's office.

Kean University educates its students in the liberal arts, the sciences and the professions; it is best known for its programs in the humanities and social sciences and in education, graduating the most teachers in the state of New Jersey annually, along with a physical therapy program which it holds in conjunction with the University of Medicine and Dentistry of New Jersey.

The Bureau of Economic Analysis calculated that the county's gross domestic product was $34.4 billion in 2021, which was ranked eighth in the state and was a 2.4% increase from the prior year.

At 0.15 miles, Route 59, located entirely in Union County, is the shortest state highway in New Jersey.

[93][94][95][96][97] Freight service is provided by on Conrail's Lehigh Line and Chemical Coast Branch.

Freight and passenger rail service was provided by the Rahway Valley Railroad from 1897 until 1992 when the short line closed due to lack of customers.

[100] The southern portion of Newark Liberty International Airport is located in Elizabeth, within Union County.

[103] A path could run directly from Summit to the Arthur Kill in Linden, New Jersey on the Rahway Valley Railroad and the Staten Island Rapid Transit line.

[104] "If Summit is able to complete the project, it might help other parts of the greenway come through," said Union County Public Relations Coordinator, Sebastian Delia.

It runs through Kean University and Liberty Hall Museum on the river's way to the Arthur Kill.

[127] Another notable course In 1869, the Union County Historical Society of New Jersey was incorporated.