Inside USPS

Decoding the Code

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You use ZIP Codes™ on a regular basis. When you fill out forms. When you address letters and packages. They’ve been around for 51 years. But do you know why the ZIP Code was created or even what ZIP™ stands for?

The Zoning Improvement Plan (ZIP) Code was introduced on July 1, 1963, as a way to better handle increasing volumes of mail around the country.

The five digits actually have specific functions: the first number in the code represents a general geographic area of the nation, “0” in the East, moving to “9” in the West. The next two numbers represent regional areas, and the final two identify specific Post Offices™.

The nine-digit ZIP+4® code was introduced in 1983. The extra four numbers allow mail to be sorted to a specific group of streets or to a high-rise building. In 1991, two more numbers were added so that mail could be sorted directly to a residence or business.

There are also ZIP Codes designated for high-volume addresses, such as government agencies and large businesses, PO Boxes™ and military addresses (APO/FPO/DPO).




The cartoon figure, Mr. ZIP®, was adopted by the Postal Service as the trademark for the ZIP Code. Mr. ZIP was unveiled by the Post Office Department at a convention of postmasters in October 1962. Mr. ZIP, who has no first name, appeared in many public service announcements and advertisements urging postal customers to use the five-digit ZIP Code. Within four years of his appearance, eight out of ten Americans knew who Mr. ZIP was and what he stood for.

Today, the use of ZIP Codes extends far beyond the original use to improve the mailing industry. Delivery services other than the Postal Service require a ZIP Code and they are a fundamental component of the nation’s 911 emergency system.