What does the 'I' in an American ZIP code stand for?

ZIP Codes are a system of postal codes used by the United States Postal Service since 1963. The term ZIP, an acronym for Zone Improvement Plan, was chosen to suggest that the mail travels more efficiently, and therefore more quickly (zipping along), when senders use the code in the postal address. The basic format consists of five digits. An extended 'ZIP+4' code, introduced in 1983, includes the five digits of the ZIP Code, a hyphen, and four additional digits that determine a more specific location within a given ZIP Code.

The term ZIP Code was originally registered as a servicemark by the U.S. Postal Service, but its registration has since expired. USPS style for ZIP is all caps and the "C" in "Code" is also capitalized, although style sheets for some publications use sentence case or lowercase.

More Info: en.wikipedia.org

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60 Comments

Leida Toro

Joe Leonard, That is exactly the question...reread it.

mikantcol

Kevin Dale Streets, Z-"Zone" Improvement P- "Plan". There, you have it.. Read.

billyboy915

Kevin Dale Streets, Did you even read as far as the second sentence in the explanation? The answer to your question is right there!

Jacqueline Tattam

Excellent Q & A

Ketan Patel

Some people have nothing better to do than whine. Great Q & A btw.

lucasmats

Perhaps it's because I remember what the initialism Zip was and the map indicating what region the first three numbers represented, I readily knew what was being asked. Acceptance was initially difficult as the sender sometimes didn't know the new Zip of the receiver Often we received mail without the zip. Acceptance was made easier because the formal address already had the post office number. I even remember Zippy the mascot and Lincoln on the pinkish four cent postage stamp.

Stevie G

Jackie Gillespie Becker, This is a global quiz site and I am not American. I like to give a bit of diversity to my questions.

Kath Thomson

Always wondered what it stood for. Most other countries call it Postal Code.

Lynne Zeman

Interesting info. Thanks Stevie

Jackie Gillespie Becker

American again!

Paul Bison

What does the "I" in an American ZIP code stand for? How can that be said to be a trick question? Which other "I" is there, apart from the one in ZIP?

Frank Sherwood

Janette Will, ZIP is a postcode. The first two digits place it in a state (or area in the state), the third digit further defines zone/area in the state and the last two are the post office itself.

popeyenys

I remember when I was very young. Mail was so important. Using the Zip Code was stressed over and over again. There will always be mail but it's lost it's preeminence with the advance of technology.