Acronym for ZIP code?

I have asked a friend of mine what ZIP stands for in ZIP code and he looked at me and said it was the area code for cities etc. I know what a ZIP code is but what does ZIP stand for?

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'ZIP" was coined by the US Postal Service to suggest that by using those postal code numbers, delivery service would be speeded up.

[i]Zip /i = move very fast.
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Hi Mister Micawber!

Thank you for your explanation. Meanwhile I’ve done some more research myself and have come up with this: Zone Improvement Plan.

By the way, is there really such a word like speeded up? I thought speed was irregular and the past form is sped?

So, you can say speeded as well as sped? It’s probably like learned and learnt? As for Zone Improvement Plan, I found that expression on Acronymfinder.com.

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Good for you-- always trust Acronymfinder over one’s own faulty memory.

Not so much like learned/learnt, I think-- which are more spelling differences than regular/irregular alternatives. More like lighted/lit. Some old irregular verbs are in the evolutionary process of regularizing.
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