Area codes 201 and 551

Area codes 201 and 551 are the North American telephone area code for the state of New Jersey covering most of Hudson and Bergen counties. Major cities in the area code include Bayonne, Jersey City, Hoboken, Hackensack, Secaucus, Englewood and Englewood Cliffs. 201 is the historical area code, first established, while 551 is an overlay covering the same area.

201 was the first original area code when AT&T devised the North American Numbering Plan in 1947. It originally covered the entire state of New Jersey. Having only one area code for the entire state which is the most densely populated state in the US, was unusual. New Jersey is centered between the New York metropolitan area in the north east and the Delaware Valley with the suburbs of Philadelphia in the south west.

In 1958, 201 was restricted to northern New Jersey, when southern New Jersey, including the state capital, Trenton, the southern Jersey Shore and the New Jersey side of the Delaware Valley, was assigned area code 609. For the next 33 years, area code 201 served Bergen, Hudson, Ocean, Essex, Union, Morris, Passaic, Hunterdon, Somerset, Middlesex, Monmouth, Sussex and Warren counties--a region largely coextensive with the New Jersey side of the New York City area.