How is a postal ZIP code determined?

star_gazer

The United States Post Office Department (USPOD) implemented postal zones for large cities in 1943. For example: Mr. John Smith 3256 Epiphenomenal Avenue Minneapolis 16, Minnesota The "16" is the number of the postal zone within the city. By the early 1960s a more general system was needed, and on July 1, 1963, non-mandatory ZIP codes were announced for the whole country. Simultaneously with the introduction of the ZIP code, two letter state abbreviations were introduced. These were to be written with both letters capitalized. Jan 08 11, 1:59 PM

star_gazer

The reason for the two-letter abbreviations is that it was thought that a long city name coupled with a multi-letter state abbreviation (e.g. Mass. for Massachusetts) would be too long for address labels used on magazines when the ZIP code was added. Robert Moon, an employee of the post office, is considered the father of the ZIP code; he submitted his proposal in 1944 while working as a postal inspector. The post office gives credit to Moon for only the first three digits of the ZIP code, which describe the sectional center facility (SCF) or "sec center." An SCF is a central mail processing facility with those three digits. The SCF sorts mail to all post offices with those first three digits in their ZIP codes. The mail is sorted according to the final two digits of the ZIP code and sent to the corresponding post offices in the early morning. Sectional centers do not deliver mail and are not open to the public (though the building may include a post office open to the public), and most of the workers are employed to work night shift. Mail picked up at post offices is sent to their own SCF in the afternoon, where the mail is sorted overnight. In the cases of large cities, the last two digits coincided with the older postal zone number,[citation needed] thus: Mr. John Smith 3256 Epiphenomenal Avenue Minneapolis, Minnesota 55416 http://en.wikipedia.org/wiki/ZIP_code Jan 08 11, 1:59 PM

Baloo55th

The UK postal code is simpler in some ways, and more specific. The first letter(s) indicate the postal town for main sorting purposes (or in the case of N, NE, NW, SE, SW, E, EC and W this is the London postal area - S is NOT London south, but is Sheffield). Birmingham, Liverpool, Manchester, Sheffield and Glasgow are single letters, all others are two. Then comes a district number within that letter - PR8 being the south end of Southport (PR being Preston). (Some London ones then have a letter.) This is the outward code, and directs to the local postal town/London area. The last part is always one number and two letters, like 9AY, and this is the inward code. This pinpoints the address precisely when coupled with the house number. There are some codes that apply only to one business. Postal codes are the main way of inputting an address into a satnav in the UK, and are used by insurance companies for assigning premiums to different areas. Sone codes are limited in area - WN (Wigan) is virtually only Wigan, while SY (Shrewsbury) covers as far as Aberystwyth. Most letters show the main town name, except Blackpool's FY which stands for Fylde, and IG which I've never worked out... UK post codes do not follow administrative boundaries (but may do if they feel like it), and may cross county boundaries and even national ones (SY for example). See http://en.wikipedia.org/wiki/Postal_code for all sorts of places. Jan 08 11, 3:22 PM

satguru

Sorry Baloo, you missed a couple for London, NE was eliminated when London added the numbers over 100 years ago, and was reallocated to Newcastle when it added them a lot later. It does remain on a good number of old street names in Clapton though. You forgot WC as well. IG and SM are the only two which mean nothing, while there are now a few more which are for company mass mail and relate only to that, although I've forgotten the exact one I know of. Jan 09 11, 12:40 PM

Baloo55th

I don't tend to go to WC (the London district, that is, bearing in mind another question going at the moment...) if I can help it. I do go to most of the others. I did have doubts about NE - I do go to EN at times and probably got mixed up. Company ones are usually apparently geographic, but have different numbers out of the normal sequence, like L69. Jan 09 11, 3:20 PM

satguru

There is one I saw not so long ago, it's BX and although you have the old extra numbers (SE99 I think is one but certainly a London 99) this is now designed for non geographic large companies. EN of course is Enfield despite crossing boroughs including Barnet and into Herts itself. http://en.wikipedia.org/wiki/List_of_postcode_areas_in_the_United_Kingdom#Non-geographic_postcodes Jan 10 11, 9:13 PM