Area codes 201 and 551

It was also the first area code with Direct Distance Dialing (DDD) service, when in 1951 the first direct-dialed long-distance call was made from Englewood, New Jersey to Alameda, California.

The bulk of New Jersey's population is concentrated in the large metropolitan area west of New York City in the northeast and the suburbs of Philadelphia in the southwest.

For over thirty years, area code 201 served Bergen, Hudson, Ocean, Essex, Union, Morris, Passaic, Hunterdon, Somerset, Middlesex, Monmouth, Sussex and Warren counties.

As the central region of New Jersey grew during the 1980s, the northeastern section of the state lost sizable portions of its population due to the decline of its major cities, including Newark, Paterson, Clifton, and Elizabeth.

Although the 1997 split was intended as a long-term solution, demand for new numbers continued in Hudson and Bergen counties, and another area code became necessary.

Numbering plan areas and area codes of New Jersey
Map of numbering plan area 201/551
Division of New Jersey into two numbering plan area in 1956. Howwever, it was not until July 1963, when New Jersey customers were required to dial the area code when calling to a location in the state, but outside of their own numbering plan area.