The British Post Office chose to use alpha-numeric combinations for its postal codes, the USA chose only numbers-why? Wouldn’t an alpha-numeric combination offer more addresses? The current US PO Zip codes are 9 digits long (like 02155-2885); how long before this numbers are exhausted?
Nine digits gives you a billion possible addresses. That is more than trice the current population of the US, so you could give every residence and business its own zip code, and not have any problems.
It’s partially a matter of early-adopter syndrome.
Two-digit postal zones were adopted for cities in 1943 (New York, 20, New York) and then expanded into the five-digit zip code in 1963. The U.S. could have made the five-digit zip alphanumeric - the U.K. already had its system in place by then - but probably didn’t see any need. The technology in place at the time wouldn’t have given better results from sorting. And I can testify that hand-sorting was the norm inside Post Offices in the late 60s, when I worked there summers.
Kodak sent out millions of return film-paks to customers, in stiff cardboard cases about the size of cigarette packs. To sort them, we stood at the focus of a many-rowed semicircle of mail sacks and lobbed (or heaved or skimmed or looped) the film to the sack with the correct three-digit label. If we missed and the film fell into the wrong sack, well, tough luck.
Flats - any large envelope that wasn’t a package - got sorted into huge cases of cubbyholes, also by hand.
At the other end, the carriers took the mail and stuffed it into vertical slots corresponding to individual addresses on streets. It might have been marginally more efficient to do so with individual postal codes than by street numbers, but the error rate from the senders probably overwhelmed any savings.
Zip codes made most sense for large bulk mailers or credit cards companies or utilities, and they got discounts for presorting. The rest of the system was good enough. In today’s world it could be better, but with the decline in physical mail because of the increase in electronic mail there’s probably not much point.
Exapno, I didn’t realize you lived in Rochester area (or if I did, I’ve forgotten it! :D). I’m a U of R grad.
I think that the reason that Zip + 4 hasn’t been pushed too hard on non-commercial mailers is that it really isn’t needed that much. Since private mail has to be hand sorted anyway, the +4 doesn’t help that much. It’s the bulk mail where it’s nice to have what comes in from the main central P.O. already route-sorted.
I don’t think that the British system was designed with the idea of maximising the number of postcodes in mind. It consists of four sections, area, district and smaller subdivisions. The first section, area, is not just some arbitrary letters. It’s a one- or two-digit representation of an actual postal area. M for Manchester, SO for Southampton and so on. It’s really quite an old-fashioned system and, I understand, not really central to how mail is distributed these days.
The US system is not abitrary either , if that’s what you are implying. The US is divided into 10 zones (the first digit of our zip codes). The next two digits are a hub city code. (For instance, 100 as the first three digits represents New York (Manhattan). The next two are local codes. The +4 portion is a further refinement on the local code.
No, I was questioning the OP’s implication that a system that employs letters as well as numbers necessarily yields a larger number of codes for the number of digits.
The British postcodes are nothing less than genus in their simplicity. The various parts give specific information like **Ximenean
** says. The postcode for the Balmoral Hotel in Edinburgh is EH2 2EQ.
The Outward Code: EH2
EH = the postcode area. One or two letters that identify the main office the letters initially goes to.
2 = the postcode district. Comprised of one or two numbers with the odd exception in central London IIRC. This helps to sort the item at the main office.
The Inward Code: 2EQ
2 = the Sector. A number that denotes a individual neighbourhood within a district.
EQ = the Unit code. Two letters that identify a group of approximately 15 addresses.
First, ZIP codes are exclusively American. ZIP is an acronym for “Zonal Improvment Plan” and is a specific type of postal code.
Second, while the number of combinations is mostly irrelevant, people have often noticed that it is easier to remember a shorter combination of letters and numbers than a longer combination of just numbers-- A 4 character postal code would be easier to remember than a 5 digit one. Additionally if the letters actually stand as some sort of abbreviation for a place, it gets even easier to remember, and certainly better that trying to think that ‘97xxx’ zip codes are in Oregon and ‘68xxx’ zip codes are somethere in Oklahoma, or maybe Kansas?
Canadian postal codes are also alphanumeric and resemble a simplified and regularized version of UK postal codes. For example, my home postal code starts with M. From that alone, we know that I live in Toronto.
Brit Postal codes because of the Alpha part tend to be alot easier to remember IME.
As Sunspace said, Canadian postal codes are alphanumeric, in the pattern A1A 1A1, and broadly speaking the first letter increases as you go west (my postal code starts with a T) and the north having the last letters of the alphabet. Some letters are omitted to avoid confusion - I don’t recall which ones but I’m sure someone will chime in and remind me! 
I do remember that in the early 70’s and before the address of Trinity College, University of Toronto ended in Toronto 181, Ontario. I graduated in 1975 and at that time it had just recently switched to Toronto, Ontario, M5S 1H8. I have a vague recollection of having a single digit (1) code in Ottawa when I was growing up, but I could be misremembering.
PS As anyone who watches Canadian TV around Christmas knows, Santa’s postal code is H0H 0H0.
From the Wiki… interesting read.
Absolutely, and it’s tied in with the metre created by the pairings of characters. I heard that the same thing was intended with the design of the AB12 XYZ car number plates, too.
Actually, British post codes don’t really work. They are converted to a numerical code which the sorting equipment uses. Commercial users can save money by using the numerical code on their mail straight away.
‘Don’t really work’ doesn’t really explain what you mean - if there’s a one-to-one correspondence between post codes and numerical alternatives, then surely the latter could just as easily be described as an alternative representation of the former?
Is there anyone who can answer my question about sat-navs and US zip-codes?
What question?
I have always assumed - no cite - that the UK system came out of the very old London postal districts: West (W1), East Central (EC1), etc. As we already had these on letters going to London it made sense to define new one and two alphabetic codes for other post towns.
That’s true, although other big cities’ postal districts were also incorporated into the scheme when it was implemented nation-wide - Postcodes in the United Kingdom - Wikipedia