Atherton, Calif. (94027) is the most expensive ZIP code in the nation, located in the state with the biggest concentration of pricey ZIPs in the U.S. On a city level, San Francisco lead nationally ...

They are the five numbers that stand for home. Since 1963, ZIP codes have been a part of just about every piece of mail that travels through our system. But what do those numbers stand for?

Additional numbers In 1983, a hyphen and four-digit code were added to some of the ZIP codes. The ZIP+4 code was implemented when it became difficult to sort mail based only on traditional ZIP ...

Forbes’ annual list of America’s Most Expensive Zip Codes is based on data from Altos Research, a Mountain View, Calif.-based real estate analysis firm. For this ranking, Altos calculated the ...