Oshkosh, WI

ZIP code 54903 is a PO Box ZIP code associated with Oshkosh, Wisconsin, rather than a conventional neighborhood with clearly defined boundaries. Major attractions are not generally assigned to 54903 itself. Oshkosh’s best-known landmarks—including the EAA Aviation Museum, the Oshkosh Public Museum, and the Grand Opera House—are elsewhere in the city and use other ZIP codes.