Editing ZIP Code (section)

== History ==

=== Early postal zones ===
[[File:UseZipCode.JPG|thumb|A 1963 U.S. Post Office sign featuring [[Mr. ZIP]]]]
[[File:Stamps USA, Markenheft IMG 1699.JPG|thumb|A [[Label (philately)|label]] inside a [[Postage stamp booklet|stamp booklet]] promoting the ZIP Code]]
[[File:Swinging Six Zip Code 1967.ogv|thumb|thumbtime=14:38|right|320px|A Swingin' Six video used by the post office to promote the ZIP Code]]
The early history and context of postal codes began with [[Postal code#History|postal district/zone numbers]]. The [[United States Post Office Department]] (USPOD) implemented postal zones for 124 large cities in May 1943.<ref>{{Cite web |title=A Zoning System in Development |url=https://postalmuseum.si.edu/zipcodecampaign/p2.html |archive-url=https://web.archive.org/web/20120104222751/http://www.postalmuseum.si.edu/zipcodecampaign/p2.html |archive-date=2012-01-04 |url-status=dead |publisher=Smithsonian National Postal Museum |access-date=2019-12-22}}</ref> Postmaster General [[Frank C. Walker]] explained that many experienced postal clerks were going into the army, and the zone system would enable inexperienced clerks to sort mail without having to learn the delivery area of each city carrier.<ref>{{cite news |title=Home Folks to Have P.O. Numbers Like Army Boys |url=https://www.newspapers.com/image/182725652/?terms=postal%20zone&match=1 |access-date=31 January 2023 |publisher=Minneapolis Morning Tribune |date=May 6, 1943 |archive-date=February 1, 2023 |archive-url=https://web.archive.org/web/20230201032632/https://www.newspapers.com/image/182725652/?terms=postal%20zone&match=1 |url-status=live }}</ref>

For example:

<blockquote>
<poem>
Mr. John Smith
3256 Epiphenomenal Avenue
Minneapolis ''16'', Minnesota
</poem>
</blockquote>

The "16" is the number of the postal zone in a specific city.<ref name=":0">{{Cite web|url=https://www.theatlantic.com/technology/archive/2013/04/the-bounty-zip-codes-brought-america/275233/|title=The Bounty ZIP Codes Brought America|last=Chokshi|first=Niraj|date=April 23, 2013|website=The Atlantic|language=en-US|access-date=2020-03-12|quote=...Postmaster General Edward Day in the early 1960s suggested combining Moon's three-digit code with the existing two-digit system.|archive-date=October 26, 2020|archive-url=https://web.archive.org/web/20201026095632/https://www.theatlantic.com/technology/archive/2013/04/the-bounty-zip-codes-brought-america/275233/|url-status=live}}</ref>

=== Establishment ===
By the early 1960s, a more organized system was needed. Non-mandatory five-digit ZIP Codes were introduced nationwide on July 1, 1963.<ref name=mlcdintr/><ref name=lblsccs/> The USPOD issued its ''Publication 59: Abbreviations for Use with ZIP Code'' on October 1, 1963, with the list of [[List of U.S. state abbreviations|two-letter state abbreviations]] which are generally written with both letters capitalized.<ref name=USPS>[https://about.usps.com/who-we-are/postal-history/state-abbreviations.pdf "State Abbreviations", USPS.com] {{Webarchive|url=https://web.archive.org/web/20170116005935/http://about.usps.com/who-we-are/postal-history/state-abbreviations.pdf |date=2017-01-16 }}.</ref> An earlier list, publicized in June 1963, had proposed capitalized abbreviations ranging from two to five letters.<ref name=USPS/> 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",<ref name=USPS/> 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, except for [[Nebraska]], which was changed from NB to NE in 1969 at the request of the [[Canada Post|Canada Post Corporation]], to avoid confusion with [[New Brunswick]].<ref name=USPS/>

[[Robert Moon (postal inspector)|Robert Moon]] is considered the father of the ZIP Code; he submitted his proposal in 1944 while working as a [[United States Postal Inspection Service|postal inspector]].<ref>Bullamore, Tim (2001). Robert Moon Obituary. Retrieved from https://www.independent.co.uk/news/obituaries/robert-moon-729034.html {{dead link|date=December 2019}}.</ref><ref>{{cite news | url = https://www.nytimes.com/2001/04/14/us/robert-moon-an-inventor-of-the-zip-code-dies-at-83.html | title = Robert Moon, an Inventor of the ZIP Code, Dies at 83 | first = Douglas | last = Martin | date = 2001-04-14 | newspaper = [[New York Times]] | access-date = 2017-09-23 | archive-date = February 17, 2020 | archive-url = https://web.archive.org/web/20200217102920/https://www.nytimes.com/2001/04/14/us/robert-moon-an-inventor-of-the-zip-code-dies-at-83.html | url-status = live }}</ref> 

The phrase "zone improvement plan" is credited to [[D. Jamison Cain]], a Postal Service executive.<ref name="cain">{{Cite news |url=https://www.washingtonpost.com/local/virginia-resident-pushed-the-envelope-when-zip-code-was-born-in-1963/2018/09/29/38376e7a-c28c-11e8-97a5-ab1e46bb3bc7_story.html |title=Virginia resident pushed the envelope when Zip code was born in 1963 |date=2018-09-29 |last=Kelly |first=John |newspaper=[[The Washington Post]] |access-date=2022-08-13 |archive-date=October 10, 2018 |archive-url=https://web.archive.org/web/20181010205600/https://www.washingtonpost.com/local/virginia-resident-pushed-the-envelope-when-zip-code-was-born-in-1963/2018/09/29/38376e7a-c28c-11e8-97a5-ab1e46bb3bc7_story.html |url-status=live }}</ref> The post office credits Moon with 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 fourth and fifth digits, which give a more precise locale within the SCF, were proposed by Henry Bentley Hahn Sr.<ref>{{Cite web|url=http://archiveblog.jfklibrary.org/2015/05/papers-of-h-bentley-hahn-the-man-who-invented-the-zip-code/|title=Papers of H. Bentley Hahn: The Man Who Invented the 5-Digit ZIP Code |website=Archivally Speaking |first1=Lauren |last1=Wallace |date= May 15, 2015 |publisher=John F. Kennedy Presidential Library Archives |language=en-US|access-date=2018-04-30|archive-url=https://web.archive.org/web/20180501095121/http://archiveblog.jfklibrary.org/2015/05/papers-of-h-bentley-hahn-the-man-who-invented-the-zip-code/|archive-date=2018-05-01|url-status=dead}}</ref>

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, although the building may include a post office that is open to the public, and most of their employees work the [[shift work|night shift]]. Items of mail picked up at post offices are sent to their SCFs in the afternoon, where the mail is sorted overnight. In the case of large cities, the last two digits as assigned generally coincided with the older postal zone number.<ref name=":0" />

For example:

<blockquote>
<poem>
Mr. John Smith
3256 Epiphenomenal Avenue
Minneapolis, MN{{nbsp}}{{nbsp}}554''16''
</poem>
</blockquote>

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.<ref name="mrzip">{{Cite web|title=Mr. ZIP- The nation's original 'digital' icon|url=https://about.usps.com/who-we-are/postal-history/mr-zip.pdf|url-status=dead|archive-url=https://web.archive.org/web/20090508223728/https://www.usps.com/postalhistory/_pdf/MrZIP.pdf|archive-date=2009-05-08}}</ref> The name "Mr. ZIP" was coined by D. Jamison Cain.<ref name="cain"/> Mr. ZIP was often depicted with a legend such as "USE ZIP CODE" in the [[selvage]] of panes of [[postage stamp]]s or on the covers of booklet panes of stamps.<ref name="mrzip"/> Mr. ZIP was featured prominently alongside musical group "The Swingin' Six" in a variety show that the post office used to explain the importance of using ZIP Codes.<ref>{{Cite web|date=2013-07-01|title=The US Postal Service's zip code system turns 50|url=https://www.scpr.org/programs/take-two/2013/07/01/32505/the-us-postal-services-zip-code-system-turns-50/|access-date=2020-06-16|website=Southern California Public Radio|archive-date=June 16, 2020|archive-url=https://web.archive.org/web/20200616062613/https://www.scpr.org/programs/take-two/2013/07/01/32505/the-us-postal-services-zip-code-system-turns-50/|url-status=live}}</ref>

===ZIP+4===
In 1983, the U.S. Postal Service introduced an expanded ZIP Code system that it named ''ZIP+4'', often known as "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, the new format was not adopted universally by the public.<ref>{{cite web|url=http://www.randomhistory.com/zip-code-history.html|title=Organizing America: A History of the ZIP Code|date=25 July 2014|website=RandomHistory.com|publisher=Random History|url-status=dead|archive-url=https://web.archive.org/web/20140812203838/http://www.randomhistory.com/zip-code-history.html|archive-date=12 August 2014|access-date=19 June 2017}}</ref>

Commercial customers generally apply a ZIP+4 or a delivery point code (i.e., ZIP+6) to mail as part of address normalization. They may need to do so to receive discounted postage rates.<ref>{{Cite journal |date=11 July 2013 |title=New Standards to Enhance Package Visibility |url=https://www.govinfo.gov/content/pkg/FR-2013-07-11/pdf/2013-16524.pdf |journal=[[Federal Register]] |volume=78 |issue=133 |pages=41721-41731}}</ref> The public does not need to write the ZIP+4 code, as mail is read by a [[Multiline Optical Character Reader|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]] (IMb) 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 box]]es, 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 (e.g. using the USPS's official ZIP Code Lookup tool, and being sure to enter just city and state, not the 5-digit ZIP).<ref>{{cite web |url=https://tools.usps.com/go/ZipLookupAction_input |title=ZIP Code™ Lookup {{!}} USPS |website=tools.usps.com |access-date=2020-01-23 |archive-date=December 22, 2016 |archive-url=https://web.archive.org/web/20161222044440/https://tools.usps.com/go/ZipLookupAction_input |url-status=live }}</ref>

===Postal barcode===
{{main|Intelligent Mail barcode}}
The ZIP Code is often translated into an Intelligent Mail barcode 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]]<ref>{{cite web |url=http://kb.iu.edu/data/aapk.html |title=Archived: How can I print routing barcodes on envelopes? – Knowledge Base |publisher=The Trustees of Indiana University |access-date=July 10, 2009 |archive-date=March 10, 2012 |archive-url=https://web.archive.org/web/20120310180946/http://kb.iu.edu/data/aapk.html |url-status=live }}</ref> include the feature), but this is not recommended, as the address-to-ZIP lookup tables can be significantly out of date.

Customers who send bulk mail can get a [[Discounts and allowances|discount]] on postage if they have printed the barcode and have presorted the mail. This requires more than just a simple [[typeface|font]]; [[mailing list]]s 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 [[Numerical digit|digit]]s representing the exact [[delivery point]].{{citation needed|date=April 2010}} Furthermore, mail must be sorted in a specific manner to an 11-digit code with at least 150 mailpieces for each qualifying ZIP Code. It must be accompanied by documentation confirming this. These steps are usually done with PAVE-certified software that prints the barcoded address labels and the barcoded sack or tray tags.{{citation needed|date = November 2018}}

The assignment of delivery point digits (the 10th and 11th digits) ensures that every mailable point in the country has an 11-digit number. The delivery-point 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.<ref>{{cite web |url=http://www.ribbs.usps.gov/files/CASS/TECHNICAL_GUIDES/CASSTECH.PDF#page=40 |format=PDF |title=CASS Technical Guide |publisher=United States Postal Service |page=40 |access-date=July 10, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090419090333/http://ribbs.usps.gov/files/CASS/TECHNICAL_GUIDES/CASSTECH.PDF#page=40 |archive-date=April 19, 2009 }}</ref>