After the 5-digit ZIP code gets the mail to your local post office, the "plus 4" code gets it to your neighborhood. "Do you have to write it on your letters?" asked WCCO reporter Jason DeRusha.

English: USA 10-cent postage stamp, 1973: "It all depends on ZIP code". (Photo credit: Wikipedia) How is it that a simple five-digit ZIP code provides any insight into who you are? After ...