On July 1, 1963, the U.S. Post Office Department introduced the ZIP code program to get a handle on the heaping surplus of mail. Today, those five digits represent much more for American society. Back ...

We all have one, we know it by heart, and we share it with our neighbors. But chances are you haven't thought that much about this ubiquitous part of American life — the ZIP code. We all know about ...

Today marks the 50th anniversary of the Zone Improvement Plan, the network of ZIP codes we use for everything from mail delivery to credit card security. The U.S. Postal Service began using the ...