What the ZIP in ZIP Code Really Means

February 10, 2015

zipcodeThe ZIP code is a code we all have used countless times throughout our lives, but did you ever know what it meant?  And more importantly did you ever know what all those digits represent?   To be fair, knowing the origin of the ZIP code won’t help you get a letter or package any faster, but without it you would never receive your electric bill or that new pair of socks.

The zip code is actually an acronym for “Zone Improvement Plan”, and it just so happens the USPS intended it to mean zippy, or quick.  In 1963, the Postal Service implemented the five-digit zip code, and as a sort of marketing move, wanted to indicate that by using the zip code, the mail would get to its destination faster.  The “Improvement” part of the acronym, ZIP, was used to explain the change from the old system before 1963.  Prior to that time, the Postal Service used postal zones only in large cities.  This new system improved on the old by giving everyone a code for where they lived or worked.  The reason the Postal Service did the change was because of the growing volume of mail they were receiving.  It was a way they could sort the mail more easily.

ZIP Code zones.svgA normal, basic ZIP code is five-digits, as you know.  The first number represents a group of states, the second and third numbers represent a region in that group of states, and the fourth and fifth numbers represent addresses in that region.  In general terms, the first three numbers of the ZIP code refer to a sectional center facility, in other words, a major sorting facility.  The remaining two numbers reference the post office within that sorting facility’s area.

In 1983, the ZIP+4 system was introduced, the one we’re probably not as familiar with since it’s rarely needed on forms, applications, or even correspondence.  It’s done by the post office to ease the sorting to a specific delivery point.  It’s also used for places that receive high volumes of mail.  The newest thing from the USPS was called POSTNET, or  Postal Numeric Encoding Technique.  This is the barcode that you saw printed at the bottom of an envelope or package label.  This encoded the ZIP code and enabled machines to sort the mail.  But this too has been discontinued in favor of yet another barcode called the Intelligent Mail Barcode.  This one is the series of bars you see above the delivery address when you get a piece of mail, and it was implemented to improve efficiency and delivery even more than the other systems.

Now you can consider yourself an expert on the use of the ZIP code.

Here are some other word origin stories you might like:

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7 Sayings that Originated From the Good ‘Ole Mississippi River

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About the author 

Daniel Ganninger - The writer, editor, and chief lackey of Knowledge Stew, the author of the Knowledge Stew line of trivia books, and editor of Fact World and the Knowledge Stew sister site on Medium, our ad-free subscription sites (you can find out how to join below). I hope you find things here to annoy those around you with your new found knowledge.

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