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US ZIP Codes History

US ZIP code

The postal code system used in the United States of America is called ZIP Code. ZIP is abbreviation from Zone Improvement Program. US ZIP codes were introduced in 1963 to improve mail delivery, make it more efficiently, quickly and simplify it.

US ZIP code history

In 1943 postal zones were implemented by the postal service for large cities. But this system was not universal and a more general system was needed. So, in 1963 the new postal code system was offered by Robert Moon.

Later, in 1983 the "ZIP + 4" system was implemented by the United States Postal Service. This system is an expanded ZIP codes system and also called as "plus-four codes" or "add-on codes". Extra four digits represent a geographic area within the five-digit delivery area. These additional digits may be used for an apartment group, a city block and etc.

Sometimes ZIP code is used in the form of postal bar code and called as Postnet. Postal bar code simplifies mail sorting by automated machines. There are two types of Postnet: long (for expanded ZIP codes) and short (for five digit ZIP codes).

There is an example of post bar code which indicated five digit ZIP code.