Postal Service introduced an expanded ZIP Code system that it named ZIP+4, often known as 'plus-four codes', 'add-on codes', or 'add-ons'. ZIP was featured prominently alongside musical group 'The Swingin' Six' in a variety show that the post office used to explain the importance of using ZIP Codes. ZIP was often depicted with a legend such as 'USE ZIP CODE' in the selvage of panes of postage stamps or on the covers of booklet panes of stamps.

The United States Post Office used a cartoon character, which it called Mr. In 1967, these became mandatory for second- and third-class bulk mailers, and the system was soon adopted generally. In the case of large cities, the last two digits as assigned generally coincided with the older postal zone number. Items of mail picked up at post offices are sent to their own SCFs in the afternoon, where the mail is sorted overnight. Sectional centers do not deliver mail and are not open to the public, although the building may include a post office that is open to the public, and most of their employees work the night shift. 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. The SCF sorts mail to all post offices with those first three digits in their ZIP Codes. The fourth and fifth digits, which give a more precise locale within the SCF, were proposed by Henry Bentley Hahn Sr. An SCF is a central mail processing facility with those three digits. The post office credits Moon with only the first three digits of the ZIP Code, which describe the sectional center facility (SCF) or 'sec center'.

Jamison Cain, a Postal Service executive. The phrase 'zone improvement plan' is credited to D. Robert Moon is considered the father of the ZIP Code he submitted his proposal in 1944 while working as a postal inspector. 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 Post Office Department, to avoid confusion with New Brunswick. 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. An earlier list, publicized in June 1963, had proposed capitalized abbreviations ranging from two to five letters. The USPOD issued its Publication 59: Abbreviations for Use with ZIP Code on October 1, 1963, with the list of two-letter state abbreviations which are generally written with both letters capitalized. īy the early 1960s, a more organized system was needed, and non-mandatory five-digit ZIP Codes were introduced nationwide on July 1, 1963. The '16' is the number of the postal zone in a specific city. Postmaster General Frank Walker explained that many experienced postal clerks were going into the army, and the zone system would enable inexperienced clerks to sort mail without having to learn the delivery area of each city carrier. The United States Post Office Department (USPOD) implemented postal zones for 178 large cities in May 1943. The early history and context of postal codes began with postal district/zone numbers. ZIP A label inside a stamp booklet promoting the ZIP Code A Swingin' Six video used by the post office to promote the ZIP Code ZIP Code and ZIP+4 are registered trademarks of the United States Postal Service, which also registered ZIP Code as a service mark until 1997. In 1983, an extended code was introduced named ZIP+4 it included the five digits of the ZIP Code, followed by a hyphen and four digits that designated a more specific location. Introduced on July 1, 1963, the basic format comprised five digits. The term ZIP was chosen to suggest that the mail travels more efficiently and quickly ( zipping along) when senders use the code in the postal address. ( January 2024)Ī 1974 postage stamp encouraging people to use the ZIP Code on letters and parcelsĪ ZIP Code (an acronym for Zone Improvement Plan ) is a system of postal codes used by the United States Postal Service (USPS). Please consider expanding the lead to provide an accessible overview of all important aspects of the article. This article's lead section may be too short to adequately summarize the key points.

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