[[File:USA-Stamp-1973-ZIPCode.jpg|thumb|A 1974 postage stamp encouraging people to use the ZIP Code on letters and parcels]]
The '''ZIP Code''' system (an acronym for '''Zone Improvement Plan'''<ref>{{cite web |title=Flashing Across the Country: Mr. Zip and the ZIP Code Promotional Campaign |url=https://postalmuseum.si.edu/flashing-across-the-country |publisher=Smithsonian National Postal Museum |access-date=30 May 2023 |first=Abby |last=Curtin |archive-date=May 30, 2023 |archive-url=https://web.archive.org/web/20230530154715/https://postalmuseum.si.edu/flashing-across-the-country |url-status=live }}</ref>) is the system of [[postal code|postal codes]] used by the [[United States Postal Service]] (USPS). The term ''ZIP'' was chosen to suggest that the [[mail]] travels more efficiently and quickly<ref>{{Cite web|url=https://www.uspsoig.gov/sites/default/files/document-library-files/2015/rarc-wp-13-006_0.pdf|title=The Untold Story of the ZIP Code|date=April 1, 2013|publisher=U.S. Postal Service Office of Inspector General|access-date=March 11, 2020|quote=When Day unveiled the nationwide 5-digit ZIP Code at a postmasters' convention in October of 1962, he simultaneously introduced the world to 'Mr. ZIP'—the cartoon character whose body language symbolizes speedy delivery.|archive-date=December 29, 2016|archive-url=https://web.archive.org/web/20161229123814/https://www.uspsoig.gov/sites/default/files/document-library-files/2015/rarc-wp-13-006_0.pdf|url-status=dead}}</ref> ([[wikt:zip#Verb|zipping along]]) when senders include the code in the [[Address (geography)|postal address]]. ''ZIP Code'' and ''ZIP+4'' areis a registered trademarkstrademark of the United States Postal Service, which also registered ''ZIP Code'' as a [[service mark]] until 1997.,<ref>{{cite web |title=Latest Status Info |url=http://tarr.uspto.gov/servlet/tarr?regser=serial&entry=73001312 |url-status=live |archive-url=https://web.archive.org/web/20120630044408/http://tarr.uspto.gov/servlet/tarr?regser=serial |archive-date=June 30, 2012 |access-date=22 December 2019 |publisher=[[United States Patent and Trademark Office]]}}</ref> and which claims "ZIP Code" as a trademark though it is not registered.<ref>{{cite web |title=USPS Trademarks |url=https://about.usps.com/strategic-planning/cs09/CSPO_09_001.htm |access-date=26 May 2025}}</ref>
Introduced on July 1, 1963, the basic format comprisedwas five digits, the first designating a region of the country and subsequent digits localizing the destination further.<ref name="mlcdintr">{{cite news |url=https://news.google.com/newspapers?id=ubNWAAAAIBAJ&sjid=0-gDAAAAIBAJ&pg=7238%2C4744197 |work=Spokesman-Review |___location=Spokane, Washington |agency=Associated Press |title=Post office readies new area mailing code |date=June 30, 1963 |page=9}}</ref><ref name="lblsccs">{{cite news |url=https://news.google.com/newspapers?id=-LZWAAAAIBAJ&sjid=7OgDAAAAIBAJ&pg=3401%2C1173278 |work=Spokesman-Review |___location=Spokane, Washington |agency=Associated Press |title=ZIP Code is labeled a success |date=October 4, 1963 |page=6}}</ref><ref>{{Cite web |last=Terrell |first=Ellen |title=This Month in Business History: ZIP Code Introduced |url=https://guides.loc.gov/this-month-in-business-history/july/zip-code-introduced |access-date=2022-07-31 |work=Library of Congress Research Guides |language=en |date=June 28, 2013 |archive-date=October 29, 2021 |archive-url=https://web.archive.org/web/20211029214050/https://guides.loc.gov/this-month-in-business-history/july/zip-code-introduced |url-status=live }}</ref> In 1983, an extended code was introduced named ''ZIP+4''; it included the five digits of the ZIP Code, followed by a hyphen and four digits that designated a ___location even more specific than the original five.
Private carriers and the USPS use ZIP Codes to route deliveries. In addition, ZIP Codes have become a basis for breaking down demographic, marketing, and sales data for analytical purposes.
