List of counties in New Jersey

Counties of New Jersey
A clickable New Jersey county map
Location	State of New Jersey
Number	21
Populations	66,083 (Salem) – 905,116 (Bergen)
Areas	47 square miles (120 km2) (Hudson) – 805 square miles (2,080 km2) (Burlington)
Government	County government
Subdivisions	borough, city, town, township, village

There are 21 counties in New Jersey. These counties together contain 565 municipalities, or administrative entities composed of clearly defined territory; 250 boroughs, 52 cities, 15 towns, 244 townships, and 4 villages. In New Jersey, a county is a local level of government between the state and municipalities. County government in New Jersey includes a Board of Chosen Freeholders, sheriff, clerk, and surrogate (responsible for uncontested and routine probate), all of which are elected officials. Counties organized under the Optional County Charter Law may also have an elected county executive. Counties traditionally perform state-mandated duties such as the maintenance of jails, parks, and certain roads. The site of a county's administration and courts is called the county seat.

New Jersey was governed by two groups of proprietors as two distinct provinces, East Jersey and West Jersey, between 1674 and 1702. New Jersey's first counties were created as administrative districts within each province, with East Jersey split in 1675 into Bergen, Essex, Middlesex and Monmouth counties, while West Jersey's initial counties of Burlington and Salem date to 1681. The most recent county created in New Jersey is Union County, created in 1857 and named after the union of the United States when the Civil War was imminent. New Jersey's county names derive from several sources, though most of its counties are named after place names in England and prominent leaders in the colonial and revolutionary periods. Bergen County is the most populous county—as of the 2010 Census—with 905,116 people, while Salem County is the least populous with 66,083 people.