The Zip Code: A brief history
A ZIP Code is a postal code used by the United States Postal Service (USPS). Initially, the first postal zoning system had been developed during WWII, and the zip code was only a two-digit number: the first denoted the city, and the second denoted the state. But as the need for delivery expanded, so did the concept of the zip code. The term “ZIP” is short for “Zone Improvement Plan.”

Introduced in 1963, the basic format consisted of five digits. Over time, the ZIP+4 was added to add more granularity to the zip code to denote specific locations, even buildings for postal workers to deliver; it included the five digits of the ZIP Code, followed by a hyphen and four digits that designated a more specific location. At the time of introduction, the 2-digit state abbreviations were also implemented to create space on the address labels for the new codes.

The United States Postal Service (USPS) has segmented the country into 10 ZIP Code areas. The five-digit ZIP Codes begin with a digit from 0-9 that represents a region of the United States. The first digit indicates a geographical area of the country, beginning with zero in the northeastern states and ending with nine in the west. The next two numbers indicate regional areas and the final two, specific Post Offices or postal zones in larger cities. ZIP Codes are not granted or assigned by any specific border that you find on a traditional US map.
While most people think of ZIP codes as covering a specific area of geography, ZIP Codes can also represent just one location such as a building. ZIP code data is an integral part of business operations in the United States. It’s an important parameter for sending mail, managing fraud detection or researching demographic information. The ZIP codes help postal service providers to designate delivery routes.