Robert Moon (1917-2001), sometimes called 'Mr. Zip' is considered the father of the zip code or zoning improvement program, a mechanism to route mail. He developed the idea in the 1940s while working as a Postal Inspector in Philadelphia, but the Directory of Post Offices, using zip code numbers, was not delivered until 1963. He lived in Philadelphia, Chicago, Reston, Virginia, and Leesburg, Florida.