On July 1, 1963, the United States Post Office introduced the Zone Improvement Plan, or ZIP Code.ZIP codes are five-digit numbers that designate an area for the United States Postal Service.
ZIP is an acronym for Zone Improvement Plan.
A ZIP Code is a 5-digit code that identifies a specific geographic delivery area.
ZIP Codes can represent an area within a state, an area that crosses state boundaries, or a single building or company that has a very high mail volume.
See all Zip Codes by State and principal US territories