Union County's population is 523,000 in a land area of 100 square miles. Of New Jersey's 21 counties, Union County ranks 6th in population and 20th in size. It is the third most densely populated county in New Jersey. The county was established in 1857 with the county seat being Elizabeth. Several pre-Revolutionary buildings can be seen in Elizabeth. Union county is home to one of the world's largest ports for shipping containers. Princeton University was founded here in 1746.

From the 15th to 17th Centuries, the Dutch and English were drawn to this area -- then occupied by the Lenni Lenapi Indians (or Delaware tribe, as the Europeans called them) -- because of its incredibly easy access by sea. They developed the first colonial settlements in the area because of its natural beauty, vast abundance of fertile fields and natural resources, and offer of personal freedom. The development of the area was greatly helped by the crisscross network of Indian trails, which became colonial roads and, centuries later, major highways.

In the historic Elizabethtown Purchase of 1664 -- the Lenni Lenapi gave a group of English settlers title to an immense tract of land that extended from the Raritan to the Passaic Rivers, and westward for over thirty miles. It is interesting to note that the Indians believed they were selling the rights to use the land for hunting, fishing, farming and such. The English concept of "owning" land was unknown to them at that time. The purchase led to the first permanent English settlement in New Jersey. Elizabethtown was laid out along the Elizabeth River near the present Union County Courthouse. As the port of entry and first seat of New Jersey government, Elizabeth became a prominent and thriving economic center, and the leading settlement in the state.

In 1683, the General Assembly, meeting in Elizabethtown, divided East New Jersey into four counties: Bergen, Essex, Middlesex and Monmouth. What we know as Union County was originally a part of Essex County.

The creation of Plainfield in 1847 fueled the movement to secede from Essex County, to create a new county better equipped to meet the needs of the southernmost towns. The animosities between Elizabethtown and Newark heightened in 1807 when Newark replaced Elizabethtown as Essex County's seat of justice, and gradually overcame Elizabethtown in economic importance. It accelerated when Elizabeth incorporated in 1855.

Union County was officially formed by state legislature on March 19th, 1857. It was the last of New Jersey's counties to be created. Union County -- one of 17 counties in the nation to bear that name -- is the oldest of the group. While it is the second smallest of New Jersey's 21 counties (larger only than Hudson County), its half-million residents also make it the most densely populated. Again named as the County seat, Elizabethtown regained its historic economic prominence that was lost in the shadow of Newark.

Although no one is certain why the name "Union County" was chosen, some historians credit it to the growing Pre-Civil War concern to protect the federal union. Others believed it more reflected the local predilection for independence and unity, for which the southern Essex County towns had long struggled. Whatever the reason, Union County residents at that time are often portrayed as being strongly united as they moved forward together to create an equitable and forward-looking County government.

Union County is the only county in the state that operates under the County Manager form of government, which divided the government into two branches: A legislative branch, consisting of the Board of Chosen Freeholders, and an executive branch, headed by an appointed County Manager.