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.

You may know where 90210 is, but what about 76707? Meet Boulder, Colo.'s local "superhero": the Mighty Zip Code Man. David Rossteicher has memorized more than 30,000 zip codes, a skill that he shows ...