Question: My son is insisting that I can send him postcards to his name and 9-digit ZIP code, with no street address included. I don’t believe him. What’s the story and how do ZIP+4 ZIP codes work?

U.S. zip codes were designed in 1963 to tell USPS how to sort your mail — but now they might tell others how you live your life. Software company Esri’s Tapestry Segmentation project has combined U.S.