Today in History: The Birthday of the ZIP Code

• The non-mandatory five-digit ZIP Codes were inaugurated on July 1, 1963.
• It's been used for 59 years.

H. Bentley Hahn.

Photograph of H. Bentley Hahn at the ZIP Code Symposium in Pittsburgh, Pennsylvania, 16 March 1965.

Before that people in the US used the postal code.

In 1943 the USPS implemented zones for 124 urban areas. However, the old method was complicated over time as the nation's population and mail volume grew. Between 1943 and 1962, annual mail volume doubled, growing from 33 billion pieces of mail to 66.5 billion. So in the summer of 1963, the Zone Improvement Plan (ZIP Code) began was introduced to the public. The ZIP Code is part of a larger Postal Service Nationwide Improved Mail Service (NIMS) plan to improve the speed of mail delivery.

To let people use the ZIP Code, the Post Office had to advertise the new numbers. They made a mascot called Mr.ZIP and a Swingin' Six video used by the post office to promote the ZIP code.

Mr. ZIP, the United States Post Office Department mascot, promoted and explained the new ZIP Code system.

A label inside a stamp booklet promoting the ZIP code.

On June 1, 1965, the Post Office replaced the 52 separate State and territory directories with a one national postal code directory, making it simpler for users to identify codes for the mail they were sending.

In 1983, the U.S. Postal Service introduced an expanded ZIP Code system that it called ZIP+4, often called "plus-four codes", "add-on codes", or "add-ons".

In today's databases, the ZIP Code is a common approach to geographically restrict results. Governmental organizations also generate and disseminate data by ZIP code.