History of ZIP Codes

ZIP Codes were developed in the 1960s to speed up the processing of mail.


As you can imagine, as the United States became more industrialized and populated, the volume of mail greatly increased in the 20th Century. By 1943, so many postal workers who had the skill in knowing how to sort mail had left to serve in the military, that a new system of sorting the mail had to be implemented.

The Beginning of Zoning

The Post Office Department (as it was known back then) instituted a zoning system by May, 1943. For instance, mail would have an address followed by the city, zone and state such as "Boston, 5 Massachusetts." This helped new employees sort the mail. Elvis' 1962 song,"'Return to Sender" had in the lyrics, "... no such number, no such zone." Younger people today wouldn't know what he was talking about.

ZIP Codes Born

In 1963, an even more advanced system came out, the "Zoning Improvement Plan" (ZIP). The first digit designated large geographical areas starting "0" for the Northeast and increasing as it progressed southward and westward with the West Coast and Alaska beginning with a "9". The first three digits combined into a sectional center desination for large sorting facilities around the major metropolitan areas. The last two digits comprised a number for small Post Offices or zones in large cities. Every address in America had a ZIP Code. It took a few years, but Americans adopted the use of the ZIP Code in order to ensure that their mail was delivered promptly. In the 80's and 90's, postal directories were published for looking up ZIP Codes for an address. That's how GreatData.com started out verifying some of our ZIP Code information. Now it's easy to find a ZIP Code for an address, or find cities for a ZIP Code. You can click here to go to the U.S. Postal Service's web site.