 Until the founding of the Oxon Hill post office about 1960, the Fort Washington area generally used the mailing address Washington, D.C., except for the few years that Friendly had a post office.About 1980 the postal service split the Fort Washington area from Oxon Hill, defining it as a separate town name.At that time, to make mail sorting easier, they drew the boundary between the two communities to conform to already existing zip code boundaries.