The familiar five-digit number was part of a nationwide effort to modernize the mail.

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, ...

Hanna Horvath is a CERTIFIED FINANCIAL PLANNER™ and Red Venture's senior editor of content partnerships. Fox Money is a personal finance hub featuring content generated by Credible Operations, Inc.

That used to be the ZIP code for Silver Cliff, Colorado, before the U.S. Postal Service removed it from use and forced the town to use neighboring Westcliffe’s ZIP code. “We lost our identity,” said ...