To celebrate, the Chicago Post Office temporarily renamed a local postal location.
The Streeterville station was called the "Cap Streeter station" Monday in honor of George "Cap" Streeter for whom the neighborhood is named.
Customers mailing letters at the station Monday had their mail canceled with a special pictorial postmark in honor of Cap Streeter.
Monday's event was one of several for the neighborhood to mark the link between the date and the ZIP code.
