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.

The humble ZIP Code shows up in all kinds of surprising places. Planet Money looks at how it was born, how it transformed the mail and talks to one researcher who argues that it's gone too far. The ...

IN THIS WEEK’S ASK CARAY, WE’RE TALKING ABOUT ZIP CODES. THERE ARE ABOUT 66 DIFFERENT ZIP CODES IN LOUISVILLE ALONE. ONE THAT STANDS OUT IS 40041 KY. MORNING ANCHOR CARAY GRACE EXPLAINS WHY. ZIP CODES ...

The holidays were busy for mail carriers because we were busy sending packages with a familiar five-digit code. Our Planet Money team got curious, where did ZIP codes come from? Here's reporter Sally ...