From the 15th to 17th Centuries, the Dutch and English were drawn to this area, then occupied by the Lenni Lenape Indians, 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 criss-cross network of Indian trails, which became colonial roads and, centuries later, major highways.
In the historic Elizabethtown Purchase of 1664 the Lenni Lanapi gave a group of English settlers the title to an immense tract of land that extended from the Raritan to the Passaic Rivers, and westward for over thirty miles. 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.
According to 2015 U.S. Census estimates, its population was 555,786.
Kean University, a co-educational, public research university dating back to 1855 is located in Union and Hillside, serving nearly 13,000 undergraduates. 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. Union County College is the two-year community college for Union County, one of a network of 19 county colleges in New Jersey. Union County College was founded in 1933 and has campuses in Cranford, Elizabeth, Plainfield and Scotch Plains.
Passenger rail service is provided by New Jersey Transit via the Northeast Corridor, North Jersey Coast Line, Raritan Valley Line, the Morristown Line and the Gladstone Branch. NJ Transit provides bus service to the Port Authority Bus Terminal in Midtown Manhattan, as well as service to major cities in New Jersey and within Union County. The southern portion of Newark Airport is located in Elizabeth, within Union County.