On this day in 1963, the United States Postal Service gave birth to the ZIP code. "ZIP" stands for "Zone Improvement Plan," and they're designed to make sorting and delivering mail more efficient.
The idea of postal codes predates the zip code, having been introduced in 1943. They were used mostly in large cities where a number would represent a specific postal zone within the city. By the early 60's, a more organized system was needed. By October 1, 1963, the Post Office released Publication 59: Abbreviations for Use with ZIP Code, which contained the list of codes as well as the two letter state abbreviations that have been used since. Zip codes were optional at this time.
According to Publication 59, the two-letter standard was "based on a maximum 23-position line, because this has been found to be the most universally acceptable line capacity basis for major addressing systems", which would be exceeded by a long city name combined with a multi-letter state abbreviation, such as "Sacramento, Calif." along with the ZIP Code. The abbreviations have remained unchanged, with the exception of Nebraska, which was changed from NB to NE in 1969 at the request of the Canadian postal administration, to avoid confusion with the Canadian province of New Brunswick.
There are four types of ZIP Codes:
Unique: assigned to a single high-volume address
Post Office Box-only: used only for PO Boxes at a given facility, not for any other type of delivery
Military: used to route mail for the U.S. military
Standard: all other ZIP Codes.
The first three digits of the Standard code represent the part of the country the mail is going to, and the last two identify the post office within that region. Robert Moon is considered the father of the ZIP Code; he submitted his proposal in 1944 while working as a postal inspector. The post office only credits Moon with the first three digits of the ZIP Code, which describe the sectional center facility (SCF) or "sec center." An SCF is a central mail processing facility with those three digits. The fourth and fifth digits, which give a more precise locale within the SCF, were proposed by Henry Bentley Hahn Sr. The SCF sorts mail to all post offices with those first three digits in their ZIP Codes. The mail is sorted according to the final two digits of the ZIP Code and sent to the corresponding post offices in the early morning. Sectional centers do not deliver mail and are not open to the public (though the building may include a post office that is open to the public), and most of their employees work the night shift.
In 1983, the U.S. Postal Service rolled out "ZIP + 4," which added a hyphen and four additional digits to the end of the current ZIP code to speed things up even more. The first two digits of the addendum stand for a specific group of streets or cluster of large buildings, and the last two narrow it down further, specifying one side of the block or even one floor in a large building.
ZIP codes start with zero in the Northeast and get bigger as one moves south and west. There are more than 42,000 ZIP codes in the United States.
Comments
Post a Comment