ZIP (Zone Improvement Plan) codes were introduced in 1963 to help the U.S. Postal Service provide more efficient mail delivery.

Photograph by Ashlee Warren, MyShot
  • On July 1, 1963, the United States Postal Service started using ZIP codes. A ZIP (Zone Improvement Plan) code is a five-number sequence printed after the city and state on all mail sent in the United States. The ZIP code was created to make processing the mail faster and more accurate. The first digit of a ZIP code represents a collection of states, the second two digits represent a more specific state or region, and the last digits represent the most specific delivery area for that region.

    Today, many areas in the U.S. use the “ZIP+4” code, which adds an additional four numbers to the original ZIP code. These numbers give the postal service an even more specific location for the address within the ZIP code.

  • Term Part of Speech Definition Encyclopedic Entry
    region Noun

    any area on Earth with one or more common characteristics. Regions are the basic units of geography.

    Encyclopedic Entry: region
    sequence Verb

    to put in order.

    specific Adjective

    exact or precise.

    state Noun

    political unit in a nation, such as the United States, Mexico, or Australia.