International Zip Code Formats For Essays

"Post code" redirects here. For computer POST codes, see Power-on self-test.

A postal code (also known locally in various English-speaking countries throughout the world as a postcode, post code, Eircode, PIN Code or ZIP Code) is a series of letters or digits or both, sometimes including spaces or punctuation, included in a postal address for the purpose of sorting mail.

In February 2005, 117 of the 190 member countries of the Universal Postal Union had postal code systems.

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[edit]

There are a number of synonyms for postal code; some are country-specific.

  • Postal code: The general term is used in Canada.
  • Postcode: This solid compound is popular in many English-speaking countries and is also the standard term in the Netherlands.
  • Eircode: The standard term in Ireland.
  • CAP: The standard term in Italy; CAP is an acronym for codice di avviamento postale (postal expedition code).
  • CEP:The standard term in Brazil; CEP is an acronym for código de endereçamento postal (postal addressing code).
  • NPA in French-speaking Switzerland (numéro postal d'acheminement) and Italian-speaking Switzerland (numero postale di avviamento).
  • PIN code / Pincode: The standard term in India; PIN is an acronym for postal index number.
  • PLZ: The standard term in Germany, Austria, German-speaking Switzerland and Liechtenstein; PLZ is an abbreviation of Postleitzahl (postal routing number).
  • ZIP code: The standard term in the United States and the Philippines; ZIP is an acronym for zone improvement plan.

History[edit]

The development of postal codes reflects the increasing complexity of postal delivery as populations grew and the built environment became more complex. This happened first in large cities. Postal codes began with postal district numbers (or postal zone numbers) within large cities. London was first subdivided into 10 districts in 1857, and Liverpool in 1864. By World War I, such postal district or zone numbers existed in various large European cities. They existed in the United States at least as early as the 1920s, possibly implemented at the local post office level only (for example, instances of "Boston 9, Mass" in 1920 are attested,[1][2]) although they were evidently not used throughout all major US cities (implemented USPOD-wide) 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. These developed into postal codes as we define them today. (The name of US postal codes, "ZIP codes", reflects this evolutionary growth from a zone plan to a zone improvement plan [ZIP].) Modern postal codes were first introduced in the Ukrainian Soviet Socialist Republic in December 1932,[3] but the system was abandoned in 1939. The next country to introduce postal codes was Germany in 1941,[4] followed by Argentina in 1958, the United States in 1963[5] and Switzerland in 1964.[6] The United Kingdom began introducing its current system in Norwich in 1959, but they were not used nationwide until 1974.[7]

Presentation[edit]

Character sets[edit]

The characters used in postal codes are

Reserved characters[edit]

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 use alternate letters and numbers (with a space after the 3rd character) in this format: A9A 9A9[8]

In Ireland the eircode system uses the following letters only: A, C, D, E, F, H, K, N, P, R, T, V, W, X, Y. This serves two purposes:

  • to avoid confusion in OCR, and
  • it also helps to avoid accidental doubles-entendres by avoiding the creation of word look-alikes, as Eircode's last 4 characters are random.

Alphanumeric postal codes[edit]

Most of the postal code systems are numeric; only a few are alphanumeric (i.e., use both letters and digits). Alphanumeric systems can, given the same number of characters, encode many more locations. For example, while a 2 digit numeric code can represent 100 locations, a 2 character alphanumeric code using ten numbers and twenty letters can represent 900 locations.

The independent nations using alphanumeric postal code systems are:

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[edit]

ISO 3166-1 alpha-2 country codes were recommended by the European Committee for Standardization as well as the Universal Postal Union to be used in conjunction with postal codes starting in 1994,[11][12] but they have not become widely used.

Andorra, Azerbaijan, Barbados, Ecuador, Latvia and Saint Vincent and the Grenadines use the ISO 3166-1 alpha-2 as a prefix in their postal codes.

In some countries (such as in continental Europe, where a numeric postcode format of four or five digits is commonly used) the numeric postal code is sometimes prefixed with a country code when sending international mail to that country.

Placement of the code[edit]

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, China, Japan, Kyrgyzstan, Russia, Turkmenistan it is written at the beginning of an address.[citation needed]

Geographic coverage[edit]

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[edit]

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[edit]

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 (8 digit alphanumeric) 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 (24 of 100 possible codes used = 24%)
BB - one of the 226 cantons of Ecuador (for AABB 226 of 10000 codes used, i.e. 2.26%. Three cantons are not in any province)
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 (7 of 10 used, i.e. 70%)
BB - one of the 81 cantons of Costa Rica (81 of 100 used, i.e. 81%)
CC - one of the districts of Costa Rica.

In Costa Rica these codes are also used by the National Institute for Statistics and Census (INSEC).

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.[13]

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 boundaries[edit]

In France the numeric code for the departments is used as the first two 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[edit]

The first digit of the postal codes in the United States defines an area including several states. From the first three digits (with some exceptions), one can deduce the state.

Similarly, in Canada, the first letter indicates the province or territory, although the provinces of Quebec and Ontario are divided into several lettered sub-regions (e.g. H for Montreal and Laval), and the Northwest Territories and Nunavut share the letter X.

Codes defined independently from administrative areas[edit]

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 (0-9); that of the first two combined is utilized to 89%, i.e. there are 89 postal zones defined. Zone 11 is non-geographic.

Royal Mail 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.

In Brazil the 8-digit postcodes are an evolution of the 5-digit area postal codes. In the 1990s the Brazilian 5-digit postal code (illustrated), , received a 3-digit suffix , but this suffix is not directly related to the administrative district hierarchy. The suffix was created only for logistic reasons.

  • Brazilian 8-digit postal codes - A city block and its faces
  • City blocks surrounded by streets, some streets with a different 8-digit postal code (suffixes 001 to 899).

  • Faces of a city block and their extension into its interior. Each color is a 8-digit postal code, usually assigned to a side (odd or even numbered) of a street.

  • Faces of a city block and their extension between city blocks. The same colors (polygons) indicate the same postal codes.

  • The postal code assignment can be related to a land lot in the case of special codes assigned to individual land lots (of large receivers). In any other case it is an error to associate the postal code with the whole land lot area: a lot may have no or more than one delivery point.

A postal code is often related to a land lot, but this is not always the case. Postal codes are usually related to access points on streets. Small or middle-sized houses, in general, only have a single main gate which is the delivery point. Parks, large businesses such as shopping centres, and big houses, may have more than one entrance and more than one delivery point. So the semantic of an address and its postal code can vary, and one land lot may have more than one postal code. In Brazil only the suffixes , that designate large post-receivers, can be assigned to lots.

Precision[edit]

Ireland[edit]

In Ireland, the new postal code system launched in 2015, known as Eircode provides a unique code for each individual address. These 7-character alphanumerical codes are in the format: A99 XXXX

While it is not intended to replace addresses, in theory simply providing a 7-character Eircode would locate any Irish delivery address.

For example, the Irish Parliament Dáil Éireann is: D02 A272

The first three digits are the routing key, which is a postal district and the last four characters are a unique identifier which relates to an individual address (business, house or apartment).

Allowed letters for positions: 123 4567

Routing Key:

Position 1: A, C, D, E, F, H, K, N, P, R, T, V, W, X, Y
Position 2: 0 to 9
Position 3: 0 to 9 with the exception of W for historical Dublin postal district D6W

Unique Identifier (positions 4,5,6 & 7):
0–9 and A, C, D, E, F, H, K, N, P, R, T, V, W, X, Y

Defined in Eircode specifications : [2]

A fully developed API is also available for integrating the Eircode database into business database and logistics systems.

You can search for any Irish address' Eircode / postal code by using the search tool on the Eircode website : [3]

Netherlands[edit]

Postal codes in the Netherlands, known as postcodes, are alphanumeric, consisting of four digits followed by a space and two letters (NNNN AA). 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 Theo Mann-Bouwmeesterlaan 75, 's-Gravenhage (the International School of The Hague).

United Kingdom[edit]

Further information: Postcodes in the United Kingdom

For domestic properties, an individual postcode may cover up to 100 properties in contiguous proximity (e.g. a short section of a populous road, or a group of less populous neighbouring roads). 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 (400 metres) apart.

The structure is alphanumeric, with the following six valid formats, as defined by BS 7666:[14]

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.

United States[edit]

In the United States, the basic ZIP Code is composed of five numbers. The first three numbers identify a specific sectional center facility—or central sorting facility—that serves a geographic region (typically a large part of a state). The next two numbers identify either an area of a city (if in an urban area) or a village/town (if in a suburban/rural area).

There is an extended format of the ZIP Code known as the ZIP+4, which contains the basic five-digit ZIP Code, followed by a hyphen and four additional digits. These digits identify a specific delivery route, such as one side of a building, a group of apartments, or several floors of a large office building. Although using the ZIP+4 offers higher accuracy, addressing redundancy, and sorting efficiency within the USPS, it is optional and not widely used by the general public. It is primarily only used by business mailers.

For high volume business mailers using automated mailing machines, the USPS has promulgated the Intelligent Mail barcode standard, which is a barcode containing the ZIP+4 code plus a two digit delivery point. This 11-digit number theoretically is unique identifier for every address in the country.

India[edit]

Postal codes are also known as PIN codes in India, PIN being the short form of Postal Index Number.[15] The Pin Code was introduced on 15 August, 1972 by India Post.

India uses a unique 6 digit code as a geographical number to identify locations in India.

There are 9 postal zones in India:

  1. Delhi, Haryana, Punjab, Himachal Pradesh, Jammu and Kashmir, Chandigarh
  2. Uttar Pradesh, Uttarakhand
  3. Rajasthan, Gujarat, Daman and Diu, Dadra and Nagar Haveli
  4. Maharashtra, Goa, Madhya Pradesh, Chhattisgarh
  5. Telangana, Andhra Pradesh, Karnataka
  6. Tamil Nadu, Kerala, Puducherry, Lakshadweep
  7. West Bengal, Odisha, Arunachal Pradesh, Nagaland, Manipur, Mizoram, Tripura, Meghalaya, Andaman and Nicobar Islands, Assam, Sikkim
  8. Bihar, Jharkhand
  9. Army Post office (APO) and Field Post office (FPO)

States and overseas territories sharing a postal code system[edit]

French overseas departments and territories use the five-digit French postal code system, each code starting with the three-digit department identifier. Monaco is also integrated in the French system and has no system of its own.

The British Crown dependencies of Guernsey, Jersey and the Isle of Man are part of the UK postcode system. They use the schemes AAN NAA and AANN NAA, in which the first two letters are a unique code (GY, JE and IM respectively).

Most of the Overseas Territories have UK-style postcodes, with a single postcode for each territory or dependency, although they are still treated as international destinations by Royal Mail in the UK, and charged at international rather than UK inland rates.The four other Overseas Territories Anguilla, Bermuda, British Virgin Islands and Cayman Islands have their own separate systems and formats.

The Pacific island states of Palau, Marshall Islands and the Federated States of Micronesia remain part of the US ZIP code system, despite having become independent states.

San Marino and the Vatican City are part of the Italian postcode system, while Liechtenstein similarly uses the Swiss system, as do the Italian enclave of Campione d'Italia and the German enclave of Büsingen am Hochrhein, although they also form part of their respective countries' postcode systems. The Czech Republic and Slovakia still uses the codes of the former Czechoslovakia, their ranges not overlapping.

Non-geographic codes[edit]

In the United Kingdom, the non-conforming postal code GIR 0AA was used for the National Girobank until its closure in 2003.[16] A non-geographic series of postcodes, starting with BX, is used by some banks and government departments.

[17]

A fictional address is also used by Royal Mail for letters to Santa Claus, more commonly known as Santa or Father Christmas:

Previously, the postcode SAN TA1 was used.[19]

In Finland the special postal code 99999 is for Korvatunturi, the place where Santa Claus (Joulupukki in Finnish) is said to live, although mail is delivered to the Santa Claus Village in Rovaniemi.[20]

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.[21] Canada Post introduced a special address for mail to Santa Claus, complete with its own postal code:

In Belgium bpost sends a small present to children who have written a letter to Sinterklaas. They can use the non-geographic postal code 0612, which refers to the date Sinterklaas is celebrated (6 December), although a fictional town, street and house number are also used. In Dutch, the address is

[22]

This translates as "1 Spain Street, 0612 Heaven". In French, the street is called "Paradise Street":

[23]

Formats[edit]

Main article: List of postal codes

Non-postal uses and economic aspects[edit]

This section needs expansion. You can help by adding to it.(December 2009)

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 (or, if used in conjunction with streetmap software, road distance). 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.[24]
  • 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[edit]

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[update], the United Kingdom Government is consulting on whether to waive licensing fees for some geographical data sets (to be determined) related to UK postcodes.

See also[edit]

Notes and references[edit]

  1. ^Lynd-Farquhar Co (1920). "Advertisement for machine tools, 1920". American Machinist: 388. 
  2. ^Hill, Clarke & Co, Inc (1920). "Advertisement for a drill press, 1920". American Machinist: 389. 
  3. ^"The First Postal (ZIP) Code in the World". Ukrainian Philatelic and Numismatic Society. 2009-04-20. Retrieved 2010-03-04. 
  4. ^"The history of the postcode". Deutsche Post. Retrieved 2010-10-10. 
  5. ^"ZIP (Zone Improvement Plan) Code". International Paper Company. Retrieved 2010-10-10. 
  6. ^"Company History: Schweizerische Post-Telefon-und-Telegrafen-Betriebe". Funding Universe. Retrieved 2010-10-10. 
  7. ^"A short history of the postcode". The Independent. Archived from the original on 2011-02-25. Retrieved 2014-06-25. 
  8. ^"GreatData.com (a licensee of Canada Post data)". Retrieved 8 February 2013. 
  9. ^"Post Code Project Suspended Indefinitely". Press Release 07 published in Daily Gleaner. Jamaica Post. 2007-02-12. Retrieved 2010-03-04. 
  10. ^"List of postal codes in Peru". Wikipedia. 2016-12-19. 
  11. ^da Cruz, Frank (2008-05-17). "Frank's Compulsive Guide to Postal Addresses". Columbia University. Retrieved 2008-06-04. 
  12. ^Formatting an international address(PDF), Universal Postal Union, January 2010, p. 13, retrieved 2010-09-26 
  13. ^http://www.postakodumne.com | Posta Kodum Ne - Postal Code Reference for Turkey
  14. ^"BS7666 Address". Data Standards Catalogue. UK National Archives. 2 October 2009. Archived from the original on 28 January 2013. Retrieved 15 August 2015. 
  15. ^"Indian Pin Code Tool bskud.com". bskud.com. Retrieved 2018-01-13. 
  16. ^40 facts about the postcode to mark 40th anniversary as vital part of daily life, Daily Mirror, 26 August 2014
  17. ^VAT: insolvency, GOV.UK
  18. ^Who answers all the letters sent to Father Christmas?, Daily Telegraph, 5 December 2013
  19. ^Santa: 'I'm not a Superman, but I do exist', BBC News Online, 11 December 2002
  20. ^Not For Parents Travel Book, Lonely Planet, 2012, page 84
  21. ^Canada Post (27 January 2007). "Over one million children write letters to Santa". Retrieved 27 April 2009. 
  22. ^Ook dit jaar, helpt bpost de Sint, bpost
  23. ^Cette année également, bpost apporte son aide à Saint-Nicolas, bpost
  24. ^Charles Arthur. "Guardian newspaper article on postcodes". Theguardian.com. Retrieved 2018-02-26. 

External links[edit]

1970s Soviet stamp promoting the use of postal codes
Postal codes by country:
Numeric:

  3-digit

  4-digit

  5-digit

  6-digit

  7-digit

  8-digit

  9-digit

  10-digit

Alphanumeric:

  6-digit

  7-digit

  8-digit

  Postal codes not in use

Map of Brazilian 5-digit postalcodes of São Paulo state. Each color shows a set of administrative areas, and the hierarchy of codes relating indirectly to them.

ZIP Codes are a system of postal codes used by the United States Postal Service since 1963. The term ZIP is an acronym for Zone Improvement Plan;[1] it was chosen to suggest that the mail travels more efficiently and quickly (zipping along) when senders use the code in the postal address. The basic format consists of five digits. An extended 'ZIP+4' code was introduced in 1983 which includes the five digits of the ZIP Code, followed by a hyphen and four additional digits that determine a more specific location.

The term ZIP Code was originally registered as a servicemark by the U.S. Postal Service, but its registration has since expired.[2]

History[edit]

Early history and five-digit ZIP Codes[edit]

The early history and context of postal codes began with postal district/zone numbers. The United States Post Office Department (USPOD) implemented postal zones for numerous large cities in 1943[3]. For example:

Mr. John Smith

3256 Epiphenomenal Avenue

Minneapolis 16, Minnesota

The "16" was the number of the postal zone from the specific city.

By the early 1960s, a more organized system was needed, and non-mandatory five-digit ZIP Codes were introduced nationwide on July 1, 1963. The USPOD issued its Publication 59: Abbreviations for Use with ZIP Code on October 1, 1963, with the list of two-letter state abbreviations which are generally written with both letters capitalized.[4] An earlier list in June had proposed capitalized abbreviations ranging from two to five letters.[4] According to Publication 59, the two-letter standard was "based on a maximum 23-position line, because this has been found to be the most universally acceptable line capacity basis for major addressing systems",[4] which would be exceeded by a long city name combined with a multi-letter state abbreviation, such as "Sacramento, Calif." along with the ZIP Code. The abbreviations have remained unchanged, with the exception of Nebraska, which was changed from NB to NE in 1969 at the request of the Canadian postal administration, to avoid confusion with the Canadian province of New Brunswick.[4]

Robert Moon is considered the father of the ZIP Code; he submitted his proposal in 1944 while working as a postal inspector.[5] The post office only credits Moon with 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 their employees 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 coincide with the older postal zone number[citation needed] thus:

Mr. John Smith

3256 Epiphenomenal Avenue

Minneapolis, MN 55416

In 1967, these became mandatory for second and third-class bulk mailers, and the system was soon adopted generally. The United States Post Office used a cartoon character which it called Mr. ZIP to promote the use of the ZIP Code. He was often depicted with a legend such as "USE ZIP CODE" in the selvage of panes of postage stamps or on the covers of booklet panes of stamps.

In 1971 Elmira (NY) Star Gazette reporter Dick Baumbach found out the White House was not using a zip code on its envelopes. Herb Klein, special assistant to President Nixon, responded by saying the next printing of envelopes would include the zip code. That did occur.[6]

ZIP+4[edit]

In 1983, the U.S. Postal Service introduced an expanded ZIP Code system that it called ZIP+4, often called "plus-four codes", "add-on codes", or "add-ons". A ZIP+4 Code uses the basic five-digit code plus four additional digits to identify a geographic segment within the five-digit delivery area, such as a city block, a group of apartments, an individual high-volume receiver of mail, a post office box, or any other unit that could use an extra identifier to aid in efficient mail sorting and delivery. However, initial attempts to promote universal use of the new format met with public resistance and today the plus-four code is not required.[7] In general, mail is read by a multiline optical character reader (MLOCR) that almost instantly determines the correct ZIP+4 Code from the address—along with the even more specific delivery point—and sprays an Intelligent Mail barcode (IM) on the face of the mail piece that corresponds to 11 digits—nine for the ZIP+4 Code and two for the delivery point.

For Post Office Boxes, the general (but not invariable) rule is that each box has its own ZIP+4 code. The add-on code is often one of the following: the last four digits of the box number (e.g. PO Box 107050, Albany, NY 12201-7050), zero plus the last three digits of the box number (e.g., PO Box 17727, Eagle River, AK 99577-0727), or, if the box number consists of fewer than four digits, enough zeros are attached to the front of the box number to produce a four-digit number (e.g., PO Box 77, Juneau, AK 99750-0077). However, there is no uniform rule, so the ZIP+4 Code must be looked up individually for each box.[citation needed]

Postal bar code[edit]

The ZIP Code is often translated into an Intelligent Mail barcode that is printed on the mailpiece to make it easier for automated machines to sort. A barcode can be printed by the sender (some word-processing programs such as WordPerfect[8] and Microsoft Word[9] include the feature - but is not recommended as the address to ZIP lookup tables can be significantly out of date). It is better to let the post office put one on when it processes the piece. In general, the post office uses OCR technology, though in some cases a human might have to read and enter the address.

Customers who send bulk mail can get a discount on postage if they have printed the barcode themselves and have presorted the mail. This requires more than just a simple font; mailing lists must be standardized with up-to-date Coding Accuracy Support System (CASS)-certified software that adds and verifies a full, correct ZIP+4 Code and an additional two digits representing the exact delivery point.[citation needed] Furthermore, mail must be sorted in a specific manner to an 11 digit zip with at least 150 mailpieces for each qualifying ZIP code and must be accompanied by documentation confirming this. These steps are usually done with PAVE-certified software that also prints the barcoded address labels and the barcoded sack or tray tags.

This means that every single mailable point in the country has its own 12-digit number (at least in theory). The delivery-point digits (the 10th and 11th digits) are calculated based on the primary or secondary number of the address. The USPS publishes the rules for calculating the delivery point in a document called the CASS Technical Guide.[10] However, when confronted with two addresses like 18 and 18C, often CASS will assign the same 12-digit number to two distinct mail delivery points. The last digit is always a check digit, which is obtained by summing all 5, 9 or 11 digits, taking the residue modulo 10 of this sum (i.e., the remainder after dividing by 10) and finally subtracting this from 10. (Thus, the check digit for 10001-0001 00 would be 7, since 1+1+1=3, 3≡3(mod 10) and 10–3=7.)

Structure and allocation[edit]

Scope and international mail[edit]

ZIP Codes designate delivery points within the United States (including territories), and overseas stations of its armed forces. There are also ZIP Codes for independent countries of the Federated States of Micronesia, the Republic of the Marshall Islands, and the Republic of Palau, each of which is integrated into the U.S. postal system under a Compact of Free Association.

Mail to U.S. diplomatic missions overseas is addressed as if it were addressed to a street address in Washington, D.C. The four-digit diplomatic pouch number is used as a building number, while the city in which the embassy or consulate is located is combined with the word "Place" to form a street name. Each mission uses a ZIP+4 Code consisting of 20521 and the diplomatic pouch number. For example, the mailing address of the U.S. Embassy in New Delhi, India would be:

Embassy of the United States of America

9000 New Delhi Place

Washington, DC 20521-9000[11]

By type and use[edit]

There are four types of ZIP Codes:

  • Unique: assigned to a single high-volume address
  • Post Office Box only: used only for PO Boxes at a given facility, not for any other type of delivery
  • Military: used to route mail for the U.S. military
  • Standard: all other ZIP Codes.

Unique ZIP Codes are used for governmental agencies, universities, businesses, or buildings that receive such extremely high volumes of mail that they need their own ZIP Codes. Government examples include 20505 for the Central Intelligence Agency in Washington, D.C.; 81009 for the Federal Citizen Information Center of the U.S. General Services Administration (GSA)[12] in Pueblo, Colorado. Examples of private address unique ZIP Codes include the headquarters of Wal-Mart (72716).

An example of a PO Box only ZIP Code is 22313, which is used for PO Boxes at the main post office in Alexandria, Virginia, such as those used by the United States Patent and Trademark Office. In the area surrounding that post office, home and business mail delivery addresses use ZIP Code 22314, which is thus a Standard ZIP Code.

In certain exceptional cases, a nominally Standard-type ZIP Code may, in practice, be used as one of the three other types. For example, the ZIP Code 43210 in Columbus, Ohio is listed as a Standard-type ZIP Code. However, since its geographic boundaries are essentially coterminous with those of The Ohio State University's main campus, it is effectively exclusive to the university even though it is not officially a "Unique"-type ZIP code.

By geography[edit]

Primary state prefixes[edit]

ZIP Codes are numbered with the first digit representing a certain group of U.S. states, the second and third digits together representing a region in that group (or perhaps a large city) and the fourth and fifth digits representing a group of delivery addresses within that region. The main town in a region (if applicable) often gets the first ZIP Codes for that region; afterward, the numerical order often follows the alphabetical order.[citation needed] Because ZIP Codes are intended for efficient postal delivery, there are unusual cases where a ZIP Code crosses state boundaries, such as a military facility spanning multiple states or remote areas of one state most easily serviced from a bordering state. For example, ZIP Code 42223 serves Fort Campbell, which spans Christian County, Kentucky and Montgomery County, Tennessee, and ZIP Code 97635 includes portions of Lake County, Oregon and Modoc County, California.

In general, the first three digits designate a sectional center facility, the mail sorting and distribution center for an area. A sectional center facility may have more than one three-digit code assigned to it. For example, the Northern Virginia sectional center facility in Merrifield is assigned codes 220, 221, 222 and 223. In some cases, a sectional center facility may serve an area in an adjacent state, usually due to the lack of a proper location for a center in that region. For example, 739 in Oklahoma is assigned to Liberal, Kansas; 865 in Arizona is assigned to Gallup, New Mexico; and 961 in California to Reno, Nevada.

In terms of geographic location, many of the lowest ZIP Codes, which begin with '0', are in the New England region. Also in the '0' region are New Jersey (non-contiguous with the remainder of the '0' area), Puerto Rico, the U.S. Virgin Islands and APO/FPO military addresses for personnel stationed in Europe, Africa, Southwest Asia and aboard vessels based in the waters adjoining those lands. The lowest ZIP Code is in Holtsville, New York (00501, a ZIP Code exclusively for the U.S. Internal Revenue Service center there).[13] Other low ZIP Codes are 00601 for Adjuntas, Puerto Rico; 01001 for Agawam, Massachusetts, and the zip codes 01002 and 01003 for Amherst, Massachusetts; 01002 is used for mail in town, while 01003 is reserved for the University of Massachusetts Amherst. Until 2001, there were six ZIP Codes lower than 00501 that were numbered from 00210 to 00215 (located in Portsmouth, New Hampshire) and were used by the Diversity Immigrant Visa program to receive applications from non-U.S. citizens.[citation needed]

The numbers increase southward along the East Coast, such as 02115 (Boston), 10001 (New York City), 19103 (Philadelphia), 21201 (Baltimore), 20008 (Washington, D.C.), 30303 (Atlanta) and 33130 (Miami) (these are only examples, as each of these cities contain several ZIP Codes in the same range). From there, the numbers increase heading westward and northward east of the Mississippi River, southward west of the Mississippi River, and northward on the West Coast. For example, 40202 is in Louisville, 50309 in Des Moines, 60601 in Chicago, 63101 in St. Louis, 77063 in Houston, 80202 in Denver, 94111 in San Francisco, 98101 in Seattle, and 99950 in Ketchikan, Alaska (the highest ZIP Code).

The first digit of the ZIP Code is allocated as follows:

  • 0 = Connecticut (CT), Massachusetts (MA), Maine (ME), New Hampshire (NH), New Jersey (NJ), New York (NY, Fishers Island only), Puerto Rico (PR), Rhode Island (RI), Vermont (VT), Virgin Islands (VI), Army Post Office Europe (AE), Fleet Post Office Europe (AE)
  • 1 = Delaware (DE), New York (NY), Pennsylvania (PA)
  • 2 = District of Columbia (DC), Maryland (MD), North Carolina (NC), South Carolina (SC), Virginia (VA), West Virginia (WV)
  • 3 = Alabama (AL), Florida (FL), Georgia (GA), Mississippi (MS), Tennessee (TN), Army Post Office Americas (AA), Fleet Post Office Americas (AA)
  • 4 = Indiana (IN), Kentucky (KY), Michigan (MI), Ohio (OH)
  • 5 = Iowa (IA), Minnesota (MN), Montana (MT), North Dakota (ND), South Dakota (SD), Wisconsin (WI)
  • 6 = Illinois (IL), Kansas (KS), Missouri (MO), Nebraska (NE)
  • 7 = Arkansas (AR), Louisiana (LA), Oklahoma (OK), Texas (TX)
  • 8 = Arizona (AZ), Colorado (CO), Idaho (ID), New Mexico (NM), Nevada (NV), Utah (UT), Wyoming (WY)
  • 9 = Alaska (AK), American Samoa (AS), California (CA), Guam (GU), Hawaii (HI), Marshall Islands (MH), Federated States of Micronesia (FM), Northern Mariana Islands (MP), Oregon (OR), Palau (PW), Washington (WA), Army Post Office Pacific (AP), Fleet Post Office Pacific (AP)

Secondary regional prefixes (123xx) and local ZIP Codes (12345)[edit]

See also: List of ZIP code prefixes

The next two digits represent the sectional center facility (SCF) (e.g. 477xx = Vanderburgh County, Indiana), and the fourth and fifth digits represent the area of the city (if in a metropolitan area), or a village/town (outside metro areas): 47722 (4=Indiana, 77=Vanderburgh County, 22=University of Evansville area). When a sectional center facility's area crosses state lines, that facility is assigned separate three-digit prefixes for the states that it serves.

In some urban areas, like 462 for Marion County, Indiana, the three-digit prefix will often exist in one county, while, in rural and most suburban areas, the prefix will exist in multiple counties; for example, the neighboring 476 prefix is found in part or entirely in six counties: Gibson, Pike, Posey, Spencer, Vanderburgh, and Warrick. In some cases, an urban county may have more than one prefix. This is the case with Allen (467, 468), Lake (464, 463), St. Joseph (465, 466), and Vanderburgh (476, 477) Counties. Cities like Chicago, Houston, Los Angeles, and New York City have multiple prefixes within their city limits. In some cases, these may be served from the same SCF, such as in San Diego County, California, where the three-digit prefixes 919 and 920 are used for suburban and rural communities, and 921 for the city of San Diego itself, although all three are processed through the same SCF facility.[citation needed]

Despite the geographic derivation of most ZIP Codes, the codes themselves do not represent geographic regions; in general, they correspond to address groups or delivery routes. As a consequence, ZIP Code "areas" can overlap, be subsets of each other, or be artificial constructs with no geographic area (such as 095 for mail to the Navy, which is not geographically fixed). In similar fashion, in areas without regular postal routes (rural route areas) or no mail delivery (undeveloped areas), ZIP Codes are not assigned or are based on sparse delivery routes, and hence the boundary between ZIP Code areas is undefined. For example, some residents in or near Haubstadt, Indiana, which has the ZIP Code 47639, have mailing addresses with 47648, the ZIP Code for neighboring Fort Branch, Indiana, while others living in or near Fort Branch have addresses with 47639. Many rural counties have similar logistical inconsistencies caused by the aforementioned sparse delivery routes, often known as Rural Routes or by some other similar designation.

For example, almost all U.S. government agencies in and around the capital are assigned ZIP Codes starting with 20200 to 20599, which are Washington, D.C. ZIP Codes, even if they are not located in Washington itself. While the White House itself is located in ZIP Code 20006, it has the ZIP Code 20500. The Nuclear Regulatory Commission is located in Rockville, Maryland, at ZIP Code 20852, but has been assigned by the Postal Service the address "Washington, DC 20555".

In similar manner, the ZIP Code for the Metropolitan Washington Airports Authority, a federally chartered independent authority, is 20001-6000[14], even though the physical address of the Authority's office, "1 Aviation Circle",[15] is in Arlington, Virginia.[citation needed]

One current exception to this rule is the United States Patent and Trademark Office (USPTO). When the USPTO was located in the Crystal City neighborhood in Arlington, Virginia, it was assigned by the Postal Service the address "Washington, DC 20231" despite being physically located in ZIP Code 22202. However, the USPTO now uses a ZIP Code (22313-1450 in ZIP+4) assigned to its current PO box in Alexandria, Virginia.[16]

In rare circumstances, a locality is assigned a ZIP Code that does not match the rest of the state. In even rarer cases a ZIP Code may cross state lines. Usually, this occurs when the locality is so isolated that it is most conveniently served from a sectional center in another state. Examples:

  • Fishers Island, New York, bears the ZIP Code 06390 and is served from Connecticut because the only ferry service is to Connecticut – all other New York ZIP Codes (excepting those at Holtsville for the IRS) begin with "1".
  • Returned government parcels from Washington, D.C. are sent to ZIP Codes beginning with "569" so that returned parcels are security checked at a remote facility (this was put into place after the 2001 anthrax attacks).
  • Some Arkansas roads north of Bull Shoals Lake can best be accessed by the Protem, Missouri, delivery unit (ZIP Code 65733).
  • Fort Campbell (ZIP Code 42223), primarily in Tennessee, but the main entrance is in Kentucky.

ZIP Codes and previous zoning lines[edit]

A ZIP Code's address and the city name written on the same line do not necessarily mean that address is within the boundaries of that city. The Postal Service designates one preferred place name for each ZIP Code. This may be an incorporated town or city, a subentity of a large city or an unincorporated census-designated place, or a small unincorporated community. Additional place names may be recognized as acceptable for a certain ZIP Code. Still, others are deemed not acceptable, and if used may result in a delay in mail delivery.

Preferred place names are generally the city or town in which the address is located. However, for many cities that have incorporated since ZIP Codes were introduced, the city name is not the preferred place name. Many databases automatically assign the preferred place name for a ZIP Code, without regard to any acceptable place names. For example, Centennial, Colorado is divided among seven ZIP Codes assigned to Aurora, Englewood, or Littleton as its preferred place names; none of these seven ZIP Codes carries "Centennial" as a preferred name, and in the ZIP Code directory, Centennial addresses are listed under those three cities. Since it is acceptable to write "Centennial" in conjunction with any of the seven ZIP Codes, one can write "Centennial" in an address in Aurora, Englewood, or Littleton, as long as it is in one of the shared ZIP Codes.

Acceptable place names are usually added to a ZIP Code in cases where the ZIP Code boundaries divide them between two or more cities, as in the case of Centennial. However, in many cases, only the preferred name can be used, even when many addresses in the ZIP Code are in another city. People sometimes must use the name of a post office rather than their own city.

One extreme example is ZIP Code 85254; it was assigned the place name Scottsdale, Arizona because it is served by the Scottsdale post office, but 85% of its territory is inside the city limits of neighboring Phoenix. Another notorious example is an entire neighborhood of the city of Los Angeles known as Beverly Hills Post Office. Naturally, its residents prefer the more glamorous Beverly Hills address and 90210 ZIP Code, but this regularly causes problems with an emergency response when dispatchers have to sort out whether a given home in 90210 is in Los Angeles or Beverly Hills.

Similarly, Missouri City, Texas, straddles Harris and Fort Bend counties. The portion within Harris County is within the ZIP Code 77071, which must use the city name of Houston instead of Missouri City. At the same time, a small portion of the city of Houston is in Fort Bend County in the ZIP Code 77489, and residents there must use the name Missouri City for their address even though they are in Houston.

This also occurs in some rural areas where portions of one town have their mail delivered to other post offices. For example, while most of the town of Plainfield, Massachusetts is in ZIP Code 01070, some sections of town are in the ZIP Code area for the neighboring town of Cummington with ZIP Code 01026. Only the preferred name of Cummington is allowed in ZIP Code 01026, so residents of parts of Plainfield must list their address as being in Cummington.

This phenomenon is repeated across the country. The previously mentioned Englewood, Colorado is an inner-ring suburb that was built out by the 1960s. Its post office served the area that is now the high-growth southern tier of the Denver metropolitan area, and ZIP Codes in this area were assigned Englewood as their preferred place name. A business community as large as downtown Denver has grown in this area, with headquarters for many internationally recognized corporations. These companies indicate Englewood as their location (the preferred postal place name), although they are located in other cities. As a result, there are really two Englewoods – the city, small and with a largely working-class residential population, and, a number of miles away, the postal Englewood, a vast suburban area of upscale subdivisions and office parks that have nothing to do with the city of Englewood yet share a split identity with it solely because of ZIP Codes. People who say they live or work in Englewood and identify closely with it may rarely enter the city. In Indiana, the ZIP Code for a town usually indicates the ZIP Code for its corresponding township, as nearly all of Indiana's small town post offices have rural routes.[citation needed]

Acceptable place names also come into play in areas where citizens identify more strongly with a particular urban center than their own municipality. For example, Allegheny County, Pennsylvania, has 130 distinct municipalities, yet many of the county's residents, and even some residents of adjacent counties, commonly use Pittsburgh, Pennsylvania as their postal address. On the opposite end of the spectrum, in some urban areas, neighborhood names may be acceptable even though they have no legal standing, such as La Jolla, California, which is the preferred place name for ZIP Code 92037, despite the fact that La Jolla is a district of San Diego, California and not a separate legal entity (this ZIP Code is also in the 919/920 sequence used by San Diego County's suburban and rural areas, not in the 921 sequence used in the remainder of the City of San Diego, even though La Jolla has always been part of San Diego).

Many ZIP Codes are for villages, census-designated places, portions of cities, or other entities that are not municipalities. For example, ZIP Code 03750 is for Etna, New Hampshire, but Etna is not a city or town; it is a village district in the town of Hanover, which itself is assigned the ZIP Code 03755. Another example is ZIP Code 08043, which corresponds to the census-designated place of Kirkwood, New Jersey, but serves the entirety of Voorhees Township. This is also the case in LaGrange, New York, a portion of which is served by the 12603 ZIP Code based in the neighboring town of Poughkeepsie. The rest of LaGrange is served by the LaGrangeville Post Office. LaGrangeville is itself not a town at all, but a section of LaGrange. Willow Grove, Pennsylvania, served by the 19090 ZIP Code, is a village that straddles the border of Upper Moreland Township and Abington Township, and that post office also serves a small portion of Upper Dublin Township. Furthermore, non-municipal place names may also share ZIP Codes with municipal place names. For example, West Windsor Township, New Jersey, is commonly referred to in most mailing databases as Princeton Junction, a census-designated place within West Windsor. Silver Spring, Maryland, (20815, 20901-20912) is neither a city nor a town, but simply the common name for an unincorporated area consisting of a large part of the lower southern portion of Montgomery County.

Postal designations for place names become de facto locations for their addresses, and as a result, it is difficult to convince residents and businesses that they are located in another city or town different from the preferred place name associated with their ZIP Codes. Because of issues of confusion and lack of identity, some cities, such as Signal Hill, California, (an enclave located entirely inside the separate city of Long Beach) have successfully petitioned the Postal Service to change ZIP Code boundaries or create new ZIP Codes so their cities become the preferred place name for addresses within the ZIP Code.

Postal designation confusion may have financial implications for local governments because mail volume is one factor used by the U.S. Census Bureau to estimate population changes between decennial census enumerations.[citation needed] Sometimes local officials in a community that is not the preferred place name for a ZIP Code but is an acceptable place name will advise residents to always use the name of the community, because if the census estimate of that town's population is low they may receive fewer funds that are computed based on population. A typical example is Paddock Lake, Wisconsin, whose preferred place name is Salem. Paddock Lake is incorporated as a village within the town of Salem, even though there are more people in the village of Paddock Lake than there are in the unincorporated parts of the town of Salem. Further confusion is caused because Silver Lake, Wisconsin, which is also a village in the town of Salem and is of similar size and status to Paddock Lake, has its own ZIP Code and post office.

In another case, the U.S. Federal Communications Commission (FCC) denied a radio station (now WNNX FM) a move requiring a change in its city of license to Sandy Springs, Georgia, largely because it was not a city (until municipal incorporation in late 2005), despite being the seventh-largest place in the state by population. The FCC cited the use of "Atlanta" on letters of support from local organizations, even though the USPS forced them to use Atlanta for 30328 until well after incorporation took effect. Currently "Sandy Springs" is only acceptable, despite none of 30328 being in Atlanta, or anywhere else outside the Sandy Springs city limit. This even applies to the ZIP Code used only for PO boxes at the Sandy Springs main post office.

Because ZIP Codes and their associated place names can ignore county lines, problems may occur where street addresses are based on quadrant location within a county. For example, 30339 spans over Vinings, Georgia and Atlanta, Georgia, in southeastern Cobb County; therefore every street address is labeled SE, and has a house number on that county's grid (according to the distance from the town square in the county seat). However, because the USPS demands the use of Atlanta, Vining's addresses are written such that they appear to be in southeast Atlanta, instead of in the opposite (northwest metro Atlanta) side.

Division and reallocation of ZIP codes[edit]

Like area codes, ZIP codes are sometimes divided and changed, especially when a rural area becomes suburban. Typically, the new codes become effective once announced, and a grace period (e.g., one year) is provided in which the new and old codes are used concurrently so that postal patrons in the affected area can notify correspondents, order new stationery, etc.[17]

In rapidly growing communities, it is sometimes necessary to open a new sectional center facility, which must then be allocated its own three-digit ZIP-code prefix or prefixes. Such allocation can be done in various ways. For example, when a new sectional center facility was opened at Dulles Airport in Virginia, the prefix 201 was allocated to that facility; therefore, for all post offices to be served by that sectional center facility the ZIP Code changed from an old code beginning with 220 or 221 to a new code or codes beginning with 201. However, when a new sectional center facility was opened to serve Montgomery County, Maryland, no new prefix was assigned. Instead, ZIP Codes in the 207 and 208 ranges, which had previously been assigned alphabetically, were reshuffled so that 207xx ZIP Codes in the county was changed to 208xx codes, while 208xx codes outside that county were changed to 207xx codes. Because Silver Spring (whose postal area includes Wheaton) has its own prefix, 209, there was no need to apply the reshuffling to Silver Spring; instead, all mail going to 209xx ZIP Codes was simply rerouted to the new sectional center facility.

On the other hand, depopulation may cause a post office to close and its associated ZIP Code to be deallocated. For example, Centralia, Pennsylvania's ZIP Code, 17927, was retired in 2002.[18]

Elkins Park, Pennsylvania, was originally issued the 19117 ZIP Code, although it lies in Montgomery County, Pennsylvania. Because of the 191 prefix, which is found only in Philadelphia with that lone exception, auto insurance companies charged higher city premiums to that suburban location. For that reason, residents petitioned the USPS for a 190-prefix ZIP Code, which is common to the inner-ring Pennsylvania suburbs of that city, and, after several attempts that were initially disapproved by the USPS, Elkins Park was finally reassigned to the 19027 ZIP Code.

ZIP Codes also change when postal boundaries are realigned. For example, at the same time at which the above-noted change in Montgomery County, Maryland, took place, and under pressure from then-mayor of Washington, D.C., Marion Barry, the USPS realigned the postal boundaries between Washington, D.C. and Maryland to match the boundary. Previously, many inner suburbs, such as Bethesda and Takoma Park, Oxon Hill, Temple Hills, Suitland, and Capitol Heights had been in the Washington, D.C., postal area. As a result of the change, ZIP Codes in Maryland beginning with 200 were changed to new ZIP Codes beginning with 207, 208 or 209, depending on their location, and ZIP Codes straddling the D.C.-Maryland line were split. For example, 20016 (Bethesda) became 20816, while the Maryland portion of 20012 (Takoma Park) became 20912.

Other uses[edit]

Delivery services[edit]

Delivery services other than the USPS, such as FedEx, United Parcel Service, and DHL, require a ZIP Code for optimal internal routing of a package.

Statistics[edit]

There are over 42,000 ZIP Codes in the United States.[19] ZIP Codes are used not only for tracking of mail but also in gathering geographical statistics in the United States. The U.S. Census Bureau calculates approximate boundaries of ZIP Codes areas, which it calls ZIP Code Tabulation Areas (ZCTAs). Statistical census data is then provided for these approximate areas. The geographic data provided for these areas includes the latitude and longitude of the center-point of the ZCTAs. There are approximately 32,000 ZCTAs. The reason that there is not one ZCTA for every ZIP Code is that PO Boxes are excluded, since only populated areas are included in the Census data.[20] The Census Bureau provides many statistical data sets for ZIP Codes, but does not keep up-to-date datasets of all ZCTAs. Complete datasets providing a similar approximate geographic extent are commercially available.

ZIP Codes are inherently discrete data, or point-based data, as they are assigned only at the point of delivery, not the spaces in between the delivery points. The U.S. Census Bureau then interpolates this discrete data set to create polygons, or areal features representing the approximate extent of the ZIP Code to use for mapping and data presentation. ZCTAs are not to be confused with ZIP Codes, and they are not updated as frequently as ZIP Codes. However, for many research and planning purposes, they are very useful and can be used with ZIP Code data.

Marketing[edit]

The data is often used in direct mail marketing campaigns in a process called ZIP-code marketing. Point-of-sale cashiers sometimes ask consumers their home ZIP Code. Besides providing purchasing-pattern data useful in determining the location of new business establishments, retailers can use directories to correlate this ZIP Code with the name on a credit card to obtain a consumer's full address and telephone number. ZIP-Coded data are also used in analyzing geographic factors in risk, an insurance-industry and banking practice pejoratively known as redlining. This can cause problems (e.g., expensive insurance) for people living near a town with a high crime rate and sharing its ZIP Code, while they live in a relatively crime-free town (see Elkins Park, Pennsylvania, above).

According to an online CNN news story by Greg Botelho posted on Thursday, February 10, 2011, "California's high court ruled Thursday that retailers do not have the right to ask customers for their ZIP Code while completing credit card transactions, saying that doing so violates a cardholders' right to protect his or her personal information."[21]

Legislative districts[edit]

ZIP Codes cannot be used to identify legislative districts. Although the website of the U.S. House of Representatives has a "Find Your Representative" feature that looks up congressional districts based on ZIP Codes alone, it often returns multiple districts corresponding to a single ZIP Code.[22][23] This is because different parts of one ZIP Code can be in different districts.[24]

Internet[edit]

A 1978 proposal for a nationwide system of community networks suggested using ZIP Codes for routing.[25]

ZIP Code data is an integral part of dealer / store locator software on many websites, especially brick-and-click websites. This software processes a user-input ZIP Code and returns a list of store or business locations, usually in the order of increasing distance from the center of the input ZIP Code. As the ZIP system is confined to the U.S. Postal network, websites that require ZIP Codes cannot register customers outside the U.S. Many sites will either purchase postal code data of other countries or make allowances in cases where the ZIP Code is not recognized.

ZIP Codes are regularly used on the Internet to provide a location in situations where an exact address is not necessary (or desirable) but the user's municipality, or at least general location, is needed. Examples (in addition to the store locator example listed above) include weather forecasts, television listings, local news, and online dating (most general purpose sites, by default, search within a given number of miles of a given ZIP Code, based on the others' entered ZIP Codes).

Credit card security[edit]

Main article: Address Verification System

ZIP Codes are used in credit card authorization, specifically Address Verification System (AVS). When a merchant collects the entire address, the ZIP Code is an important part of AVS. In some cases, the ZIP Code is the only thing used for AVS, specifically where collecting a signature, or other information is infeasible, such as pay at the pump or vending machines.

Insurance rating[edit]

ZIP Codes are used by most insurance carriers to determine the rate the customer will receive. Higher populated areas will generally receive a higher rate, but that is not always true. In some areas with a high population, the rate for comprehensive coverage can be lower because the area has a low crime rate.

See also[edit]

References[edit]

  1. ^"Mr. Zip and the ZIP Code Promotional Campaign". Smithsonian National Postal Museum. Retrieved 7 March 2013. 
  2. ^"Latest Status Info". United States Patent and Trademark Office. Retrieved July 10, 2009. 
  3. ^"A ZONING SYSTEM IN DEVELOPMENT". 
  4. ^ abcd"State Abbreviations", USPS.com.
  5. ^Tim Bullamore. Robert Moon Obituary
  6. ^"The Cornell Daily Sun 17 March 1971 — The Cornell Daily Sun". cdsun2.library.cornell.edu. Retrieved 2017-11-24. 
  7. ^"Organizing America: A History of the ZIP Code". Random History. Retrieved 19 June 2017. 
  8. ^"Archived: How can I print routing barcodes on envelopes? - Knowledge Base". The Trustees of Indiana University. Retrieved July 10, 2009. 
  9. ^"Insert a barcode into an Office document". Microsoft Corporation. Archived from the original on April 24, 2012. Retrieved July 10, 2009. 
  10. ^"CASS Technical Guide"(PDF). United States Postal Service. p. 40. Archived from the original(PDF) on April 19, 2009. Retrieved July 10, 2009. 
  11. ^"Mail Management". Diplomatic Pouch and Mail Division of the U.S. Department of State. Retrieved April 1, 2015. 
  12. ^"FCIC – About Us". Federal Citizen Information Center of the U.S. General Services Administration. Archived from the original on July 14, 2009. Retrieved July 10, 2009.  
  13. ^"Postal Facts". About.usps.com. 2013-01-16. Retrieved 2014-02-10. 
  14. ^"Validated Address". Retrieved Oct 4, 2017. 
  15. ^"Google Maps". Retrieved Oct 4, 2017. 
  16. ^"Mailing and Hand Carry Addresses for the United States Patent and Trademark Office". USPTO. Retrieved May 6, 2010. 
  17. ^Roberts, Sam (March 21, 2007). "An Elite ZIP Code Becomes Harder to Crack". The New York Times. p. C15. Retrieved July 10, 2009. 
  18. ^Wheary, Rob. "Centralia loses its ZIP". 
  19. ^"United States Postal Service FAQs". USPS. Retrieved May 27, 2011. [permanent dead link]
  20. ^"U.S. Census Bureau data provided by GreatData.com". Retrieved 5 February 2013. 
  21. ^
A 1963 U.S. Post Office sign
U.S. postage stamp, 1973: "It all depends on ZIP Code"
ZIP Code zones in the United States
Early advertisement for ZIP Code 10005

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