ZIP code

ZIP code (an acronym for "Zone Improvement Plan") is a system of postal codes used by the United States Postal Service (USPS) since 1963. The basic format consists of five digits. An extended ZIP+4 code includes the five digits of the ZIP code, followed by a hyphen and four additional digits that determine a more specific location.

History

The ZIP code system was introduced on July 1, 1963, to improve the efficiency of mail delivery. The idea was to make it easier for postal workers to sort and deliver mail by providing a more precise location. The system was developed by Robert Moon, an employee of the USPS.

Structure

A standard ZIP code is composed of five digits. The first digit represents a group of U.S. states, the second and third digits together represent a region in that group (or perhaps a large city), and the fourth and fifth digits represent a group of delivery addresses within that region.

ZIP+4 Codes

In 1983, the USPS introduced an extended ZIP+4 code. This code includes the original five digits, followed by a hyphen and four additional digits. These extra digits help to identify a more specific location, such as a city block, a group of apartments, or an individual high-volume receiver of mail.

Usage

ZIP codes are used not only for mail delivery but also for various other purposes, such as determining sales tax, insurance ratings, and credit scoring. They are also used in geographic information systems (GIS) for mapping and analysis.

ZIP Code Areas

ZIP code areas can vary significantly in size. In densely populated urban areas, a single ZIP code may cover just a few city blocks, while in rural areas, a ZIP code can cover large regions.

Related Systems

Other countries have similar postal code systems, such as the postal code in Canada, the postcode in the United Kingdom, and the PIN code in India.

See Also

• United States Postal Service
• Postal code
• Geographic information system
• Sales tax
• Credit score