Area Codes 201 and 551

201 is the North American telephone area code for the state of New Jersey covering most of Hudson and Bergen counties. It is overlaid with area code 551.

The 201 area code was one of the original area codes assigned in 1947, and was also the first area code to be assigned in the United States, as part of the North American Numbering Plan. It originally covered the entire state. This was very unusual, since New Jersey is one of the most densely populated states in the nation; it is split almost down the middle between two very large metropolitan areas--the suburbs of New York City to the north and the suburbs of Philadelphia to the south.

The area code system entered service in 1951. That year, the first direct-dialed long distance call was made from Englewood, New Jersey to Alameda, California.

In 1958, 201 was restricted to northern New Jersey, with southern New Jersey becoming area code 609.

After the split in 1958, area code 201 served the northern counties in the state: Essex, Bergen, Hudson, Union, Morris, Passaic, Hunterdon, Somerset, Middlesex, Monmouth, Sussex and Warren counties. New Jersey's southern counties, including the southern Jersey Shore and the Delaware Valley were served by 609.

As the central region of New Jersey grew during the 1980s, the northeastern section of the state lost sizable chunks of its population due to the decline of its major cities, including Newark, Paterson, Clifton, and Elizabeth. On June 8, 1991, area code 908 split off from 201; it primarily serves the North/Central regions of the state.

The northernmost counties continued to use 201, while the southern half of the state kept 609, which is the area code of Trenton, the state's capital.

During the mid-1990s, businesses began to flourish once again in North Jersey, while cell phones and internet dial-up connections proliferated. In response to the pressure for the addition of more telephone numbers, New Jersey added more area codes, going from three to six. As of June 1, 1997, Essex and Passaic counties, home to Newark and Paterson respectively (the state's first and third-most populous cities), as well as the more rural northwestern counties of New Jersey, Morris and Sussex, were broken away from area code 201 as area code 973. Hudson and Bergen counties, the state's two northeastern counties (as well as being two of the state's most densely populated counties) and the closest two counties to New York City, became the last remaining counties in the state to be served by area code 201.

As Hudson and Bergen Counties developed further, and even more telephone numbers were demanded, it was debated whether 201 should split again, or if an overlay area code should be added instead. Verizon, the dominant telephone company in New Jersey, opted for an overlay to avoid the costs and frustration associated with splitting an area code (such as customers being forced to change their numbers). However, with the implementation of the overlay area code on December 1, 2001, 10-digit dialing became mandatory. Area code 551 was created in 2001, along with area codes 862 and 848 which overlay area codes 973 and 732 respectively.