ZIP Code Download is a non-exculsive licensee of the USPS and Canada Post. Through this relationship it provides ZIP Code data and software for businesses, educational institutions, and government organizations throughout the world.

If you need a ZIP Code database, take a look at these products:
5-digit ZIP Code Databases
ZIP+4 Databases
ZIP Code by County Databases
CBSA - ZIP Code Databases
Canadian Postal Code Databases

I bet you've never thought about what the world was like before we had ZIP Codes. Yeah, I haven't really thought about it either, but such a time did exist.

ZIP Codes were first introduced in the '60s - July 1, 1963 to be exact. The change in the U.S. from a primarily agricultural economy to more of an industrial economy led to a rapid increase in business mail. When the computer finally came along, mail exploded since businesses could now easily create and print bills, account statements, form letters, advertisements, etc. The post office needed an easier way to sort and route mail.

In 1967, the 5-digit ZIP Code became mandatory on all mail. These five numbers indicate the area of the country where the mail is to be delivered (0 is in the east and 9 is in the west) and the delivery office for the mail.

A 9-digit ZIP Code (also known as the ZIP+4 Code) was introduced in 1983. These extra four numbers indicate the "delivery sector" (a small geographic area) and the "delivery segment" (one side of a street, a floor of an office building, etc.).

In 1991, two more digits were added to the ZIP Code to create an 11-digit ZIP Code. It now includes the 5-digit ZIP Code, +4 Code, and the Delivery Point (usually the last two digits of a street address). This 11-digit code is represented in barcode format (called the Delivery Point Barcode or DPBC).

Thanks to the ZIP Code, billions of pieces of mail can be sorted and routed quickly and effectively. It has helped the USPS become one of the most efficient organizations in the world.

Read more about the history of the USPS >>

Finding the right ZIP Code for an address is important. That's one of the ways that the post office knows where to deliver your letters. Here are some resources from the web that will help you find the right ZIP Code.

US ZIP Codes
ZIP+4 Lookup @ USPS.com
ZIP Code Lookup for a list of addresses
ZIP Codes Directory by State, County & City
Melissa Data Lookups
ZIPDECODE by Ben Fry

Canadian Postal Codes
Canadian Postal Code Lookup

International ZIP Codes
International ZIP Code Directory