This configuration of two area code in New Jersey remained in place for c. 33 years, until 1991, when the 201 numbering plan area was further divided to create area code 908 in its southern half.
The configuration of two area codes in New Jersey persisted for roughly 33 years, from around 1968 to 1991, at which point the 201 numbering plan area was split to form area code 908 in its southern section.