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.

I cover real estate, economics and cost of living. Capitol Hill is covered to a large extent by ZIP code 20003, which is the fourth wealthiest ZIP code ... [+] in Washington, D.C. When you’re ...

WASHINGTON — LSU's Baton Rouge campus and the St. Charles Parish community of Montz are set to get a single ZIP code if the U.S. Senate takes up legislation the House approved on a voice vote ...

ZIP code 20016 includes the Palisades, Tenleytown and Cleveland Park, and the median home value is $1.09 million. One notable address? Late Sen. Dianne Feinstein's Northwest D.C. estate ...