A postal code is a series of letters and/or digits appended to a postal address for the
purpose of sorting mail.
Once postal codes were introduced, other applications became possible.
In February 2005, 117 of the 190 member countries of the Universal Postal Union had postal code
systems.
Countries that do not have national systems include Ireland and Ghana.
Although postal codes are usually assigned to geographical areas, special codes are sometimes
assigned to individual addresses or to institutions that receive large volumes of mail, such as
government agencies and large commercial companies.
One example is the French CEDEX system.
Terms There are a number of colloquial terms for
postal code.
postal code The general term is used directly in Canada.
postcode This portmanteau is popular in many English-speaking
countries.
ZIP code The standard term in the United States and
the Philippines; ZIP is an acronym for Zone Improvement Plan.
PIN code / pincode The standard term in India; PIN is an acronym
for Postal Index Number.
History
The development of postal codes reflects the natural evolution in which postal delivery
grew more complicated as populations grew and the built environment became more complex.
This process occurred first in large cities.
The nucleus of a postal code idea thus began with postal district numbers within large
cities.
London was first subdivided into 10 districts in 1857, and Liverpool in 1864.
By World War I or possibly earlier, such postal district or zone numbers existed in various
European large cities.
They existed in the United States at least as early as the 1920s, possibly implemented
at the local post office level only, although they were evidently not used throughout all
major US cities until World War II.
By 1930 or earlier the idea of extending postal district or zone numbering plans beyond large
cities to cover even small towns and rural locales was in the air.
This was the concept that would create postal codes as we define them today.
Modern postal codes were first introduced in the Ukrainian Soviet Socialist Republic
in December 1932, but the system was abandoned in 1939.
The next country to introduce postal codes was Germany in 1941, followed by Argentina
in 1958, the United States in 1963 and Switzerland in 1964.
The United Kingdom began introducing its current system in Norwich in 1959, but completed the
nationwide introduction in 1974 only.
Presentation
Character sets The characters used in postal codes are
The arabic numerals "0" to "9" Letters of the ISO basic Latin alphabet
Spaces, hyphens Reserved characters
Postal codes in the Netherlands originally did not use the letters 'F', 'I', 'O', 'Q',
'U' and 'Y' for technical reasons.
But as almost all existing combinations are now used, these letters were allowed for new
locations starting 2005.
The letter combinations SS, SD and SA are not used for historical reasons.
Postal codes in Canada do not include the letters D, F, I, O, Q, or U, as the OCR equipment
used in automated sorting could easily confuse them with other letters and digits.
The letters W and Z are used, but are not currently used as the first letter.
The Canadian Postal Codes alternates between a letter and a number in this format: A9A
9A9 Alphanumeric postal codes
Most of the postal code systems are numeric; only a few are alphanumeric.
Alphanumeric systems can, given the same number of characters, encode many more locations.
For example: with a 2 digit numeric code we could code 10 x 10= 100 locations.
In contrast, with a 2 character alphanumeric code which uses 30 different characters, one
has 30 x 30= 900 permutations.
The independent nations using alphanumeric postal code systems are:
Argentina Brunei
Canada Jamaica(suspended in 2007 )
Malta Netherlands
Peru Somalia
Swaziland United Kingdom
Venezuela.
Countries which prefix their postal codes with a fixed group of letters, indicating
a country code, include Andorra, Azerbaijan, Barbados, Ecuador and Saint Vincent and the
Grenadines.
Country code prefixes ISO 3166-1 alpha-2 country codes were recommended
to be used in conjunction with postal codes starting in 1994, but they have not become
widely used.
The European Committee for Standardization recommends use of ISO Alpha-2 codes for international
postcodes and a UPU guide on international addressing states that "administrations may
recommend" the use of ISO Alpha-2 codes.
Andorra, Azerbaijan, Barbados, Ecuador and Saint Vincent and the Grenadines use the ISO
3166-1 alpha-2 as a prefix in their postal codes.
In some countries the numeric postal code is sometimes prefixed with a country code
when sending international mail to that country.
Placement of the code Postal services have their own formats and
placement rules for postal codes.
In most English-speaking countries, the postal code forms the last item of the address, following
the city or town name, whereas in most continental European countries it precedes the name of
the city or town.
When it follows the city it may be on the same line or on a new line.
In Belarus, Japan, Kyrgyzstan, Turkmenistan and Ukraine, it is written more to the beginning
of an address.
Geographic coverage Postal codes are usually assigned to geographical
areas.
Sometimes codes are assigned to individual addresses or to institutions that receive
large volumes of mail, e.g. government agencies or large commercial companies.
One example is the French Cedex system.
Postal zone numbers Before postal codes as described here were
used, large cities were often divided into postal zones or postal districts, usually
numbered from 1 upwards within each city.
The newer postal code systems often incorporate the old zone numbers, as with London postal
district numbers, for example.
Ireland still uses postal district numbers in Dublin.
In New Zealand, Auckland, Wellington and Christchurch were divided into postal zones, but these
fell into disuse, and have now become redundant as a result of a new postcode system being
introduced.
Codes defined along administrative borders Some postal code systems, like those of Ecuador
and Costa Rica, show an exact agreement with the hierarchy of administrative country subdivisions.
Format of 6 digit numeric postal codes in Ecuador, introduced in December 2007: ECAABBCC
EC - ISO 3166-1 alpha-2 country code AA - one of the 24 provinces of Ecuador
BB - one of the 226 cantons of Ecuador CC - one of the parishes of Ecuador.
Format of 5 digit numeric Postal codes in Costa Rica, introduced in 2007: ABBCC
A - one of the 7 provinces of Costa Rica BB - one of the 81 cantons of Costa Rica
CC - one of the districts of Costa Rica.
In Costa Rica these codes are also used by the National Institute for Statistics and
Census.
The first two digits of the postal codes in Turkey correspond to the provinces and each
province has assigned only one number.
They are the same for them as in ISO 3166-2:TR.
The first two digits of the postal codes in Vietnam indicate a province.
Some provinces have one, other have several two digit numbers assigned.
The numbers differ from the number used in ISO 3166-2:VN.
Codes defined close to administrative borders In France the numeric code for the departments
is used in the first digits of the postal code, except for the two departments in Corsica
that have codes 2A and 2B and use 20 as postal code.
Furthermore the codes are only the codes for the department in charge of delivery of the
post, so it can be that a location in one department has a postal code starting with
the number of a neighbouring department.
Codes defined indirectly to administrative borders
The first digit of the postal codes in the United States defines an area including several
states.
From the first three digits, one can deduce the state.
Codes defined independently from administrative borders
The first two digits of the postal codes in Germany define areas independently of administrative
regions.
The coding space of the first digit is fully used; that of the first two combined is utilized
to 89%, i.e. there are 89 postal zones defined.
Zone 11 is non-geographic.
The UK post designed the postal codes in the United Kingdom mostly for efficient distribution.
Nevertheless people associated codes with certain areas, leading to some people wanting
or not wanting to have a certain code.
See also postcode lottery.
Precision Netherlands
Postal codes in the Netherlands, known as postcodes, are alphanumeric, consisting of
four digits followed by a space and two letters.
Adding the house number to the postcode will identify the address, making the street name
and town name redundant.
For example: 2597 GV 75 will direct a postal delivery to the International School of The
Hague.
USA Other countries allow equally precise coding.
For example, in the United States, the delivery point barcode printed underneath an address
by postal sorting equipment is typically derived from the last two digits of the house number
and thus allows an unambiguous identification of every address in the country.
UK
For domestic properties the postcode refers to up to 100 properties in contiguous proximity.
The postcode together with the number or name of a property is not always unique, particularly
in rural areas.
For example GL20 8NX/1 might refer to either 1 Frampton Cottages or 1 Frampton Farm Cottages,
roughly a quarter of a mile apart.
The postcode plus the first line of the address, however, is always unique.
Structure is alphanumeric with the following six valid permutations, as defined by BS 7666:
A9 9AA A9A 9AA
A99 9AA AA9 9AA
AA9A 9AA AA99 9AA
There are always two halves: the separation between outward and inward postcodes is indicated
by one space.
The outward postcode covers a unique area and has two parts which may in total be two,
three or four characters in length.
A postcode area of one or two letters, followed by one or two numbers, followed in some parts
of London by a letter.
The outward postcode and the leading numeric of the inward postcode in combination forms
a postal sector, and this usually corresponds to a couple of thousand properties.
Larger businesses and isolated properties such as farms may have a unique postcode.
Extremely large organisations such as larger government offices or bank headquarters may
have multiple postcodes for different departments.
There are about 100 postcode areas, ranging widely in size from BT which covers the whole
of Northern Ireland to ZE for Shetland.
Postcode areas may also cross national boundaries, such as SY which covers a large, predominantly
rural area from Shrewsbury and Ludlow in Shropshire, England, through to the seaside town of Aberystwyth,
Ceredigion on Wales' west coast.
States and overseas territories sharing a postal code system
The British Crown dependencies of Guernsey, Jersey and the Isle of Man are part of the
UK postcode system.
They use the scheme AAN NAA, in which the first two letters are a unique code.
Eight British Overseas Territories use ten postal codes: three for Saint Helena, Ascension
and Tristan da Cunha, and one apiece for the others.
Note that the former has two ISO 3166-1 alpha-2 country codes, and the British Antarctic Territory
has none, so the number of ISO codes is eight.
British Antarctic Territory: BIQQ 1ZZ British Indian Ocean Territory: BBND 1ZZ,
ISO code: IO Falkland Islands: FIQQ 1ZZ, ISO code: FK
Gibraltar: GX11 1AA, ISO code: GI Pitcairn Islands: PCRN 1ZZ, ISO code: PN
Saint Helena, Ascension and Tristan da Cunha: Ascension Island: ASCN 1ZZ, ISO code: AC
Saint Helena STHL 1ZZ, ISO code: SH Tristan da Cunha: TDCU 1ZZ, ISO code: SH
South Georgia and the South Sandwich Islands: SIQQ 1ZZ, ISO code: GS
Turks and Caicos Islands: TKCA 1ZZ, ISO code: TC
Four other British Overseas Territories have their own systems, some use the ISO 3166-1
alpha-2 prefix: Anguilla: AI-NNNN
Bermuda: AA NN or AA AA, ISO code BM not used British Virgin Islands: VGNNNN
Cayman Islands: KYN-NNNN* French overseas territories use the five-digit
French postal code system, each code starting with the three letter department identifier.
Monaco also uses the French system.
Italy, San Marino and Vatican City use one system.
Liechtenstein and Switzerland use one system.
Slovakia and the Czech Republic base their systems on the codes of Czechoslovakia, their
ranges not overlapping.
Non-geographic codes In Finland the special postal code 99999 is
for Korvatunturi, the place where Santa Claus is said to live.
In Greenland the postal code 2412 is for Julemanden In Canada the amount of mail sent to Santa
Claus increased every Christmas, up to the point that Canada Post decided to start an
official Santa Claus letter-response program in 1983.
Approximately one million letters come in to Santa Claus each Christmas, including from
outside of Canada, and all of them are answered in the same languages in which they are written.
Canada Post introduced a special address for mail to Santa Claus, complete with its own
postal code: SANTA CLAUS
NORTH POLE H0H 0H0 In the United Kingdom, the non-conforming
postal code GIR 0AA was used for the National Girobank until its closure in 2003.
Formats
Non-postal uses and economic aspects While postal codes were introduced to expedite
the delivery of mail, they are very useful tools for several other purposes, particularly
in countries where codes are very fine-grained and identify just a few addresses.
Among uses are: Finding the nearest branch of an organisation
to a given address.
A computer program uses the postal codes of the target address and the branches to list
the closest branches in order of distance as the crow flies.
This can be used by companies to inform potential customers where to go, by job centres to find
jobs for job-seekers, to alert people of town planning applications in their area, and a
great many other applications.
Fine-grained postal codes can be used with satellite navigation systems to navigate to
an address by street number and postcode.
Geographical sales territories for representatives in the pharmaceutical industry are allocated
based on a workload index that is based upon postcode.
Availability The availability of postal code information
has significant economic advantages.
In some countries, the postal authorities charge for access to the code database.
As of January 2010, the United Kingdom Government is consulting on whether to waive licensing
fees for some geographical data sets related to UK postcodes.
See also List of postal codes
Category:Lists of postal codes Address#Mailing address format by country
Postcode Address File References
External links http:www.dmoz.orgDirectoriesPostal_Codes/
Universal Postal Union Addressing
Postcodes
Reference on World Postcodes Canadian Postal Code Lookup web page from
Canada Post Links to pages on the web with information
about postal codes Links to postal service web pages