Mondo Knows Facts
ZIP in ZIP code stands for Zone Improvement Plan
The five digit code arrived in 1963 to speed up mechanical mail sorting The United States Post Office Department launched the ZIP code on 1 July 1963, with the letters standing for Zone Improvement Plan. The first digit marks a group of states, the next two a sectional centre and the last two a delivery office. Four extra digits were added from 1983 to identify a street or building. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.
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A postcode splits into outward and inward codesThe first group sorts to a district, the second to a few streetsPostcodes enable automated optical sorting of mail envelopesAlphanumeric mail codes guide high-speed postal sorters to arrange delivery routesEnvelope gum is a starch adhesive activated by waterDextrin from cooked starch turns tacky when the flap is moistenedA letter plate hinges inward over a hoodThe flap sheds rain while the hood keeps water off the opening itselfA green wave times signals so traffic keeps rollingEach junction changes slightly later so a group of cars meets every greenZebra crossings were named after their painted stripesBritain adopted the broad striped crossing nationally in 1951 after trials
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Tags: post, addresses, sorting
ZIP in ZIP code stands for Zone Improvement Plan: the short answers
- Where does this come from, and can I check it?
- The five digit code arrived in 1963 to speed up mechanical mail sorting. The figure is taken from Smithsonian Institution, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a everyday life fact?
- Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.