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 ...

One of the most important breakthroughs in modern communication lies in an overlooked place. It’s printed onto envelopes, just below the address. Although we think nothing of the ZIP Code these days, ...

Most Americans know their ZIP code by heart. They type it into online forms, scribble it on envelopes and memorize it as part of their address. But not everyone knows the original meaning of the term.

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 ...