Zip Code Lookup

The USPS Zip Code System

The United States ZIP code system, which stands for "Zone Improvement Plan", was introduced by the United States Postal Service (USPS) in 1963 to facilitate efficient mail delivery across the country. ZIP codes are numerical codes used to identify specific geographic areas for mail delivery purposes.

A ZIP code consists of five digits, which are typically written in the format "XXXXX." In 1983, the USPS introduced ZIP+4 codes, which include the basic five-digit ZIP code followed by a hyphen and four additional digits, "XXXXX-XXXX". This further refines the delivery area to a specific street segment, building, or address range.

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Click any state on the map to discover its zip codes, which cities they cover and more.

ZIP Code Tabulation Areas (ZCTAs)

ZIP Code Tabulation Areas (ZCTAs) are statistical entities developed by the United States Census Bureau to approximate the delivery areas of U.S. ZIP codes for the purpose of census data reporting and analysis. Unlike traditional ZIP codes assigned by the United States Postal Service (USPS), which are primarily designed for mail delivery, ZCTAs are constructed to align more closely with census blocks. They provide a geographic representation of the locations that would use a particular ZIP code for mail delivery, allowing for a more accurate analysis of population and demographic data.

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Zip Code Types

The US Zip Code System is made up of four different zip code types, each playing a vital role in the US Postal Service.

Unique

Unique zip codes are typically associated with entities such as government agencies, major corporations, or large institutions that generate a significant amount of mail.

Post Office Boxes

PO Box zip codes are associated with post offices that offer the service of renting out mailboxes to individuals or businesses who prefer a secure and centralized location to receive their mail.

Military

Military zip codes are used to facilitate the delivery of mail to military bases, installations, and other addresses associated with the armed forces.

Standard

Standard zip codes are the majority of zip codes fall into the category of standard codes, representing general geographic areas across the United States.

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