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?

'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.

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

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.