Zip codes introduced

On July 1, 1963, the United State Post Office introduced non-mandatory ZIP for the entire country. Employee Robert Moon, first submitted his proposal for the idea while working as a postal inspector in 1944. In 1967, the Post Office began mandating Zip Codes for second- and third-class bulk mail.

Speaking of zip codes the Old Post Office in Washington DC built in the 1890s is a great tourist stop. It has an interior glass-roofed atrium with a food court. After lunch, take the free elevator ride to the top of the Old Post Office tower. The granite clock tower has an observation level 270 feet above the street. It offers a 360 degree view of downtown Washington, DC.

Happy travels!