During the mid-1900s, a Washington, DC address with a zip code did not necessarily mean the individual physically lived in Washington, DC. I grew up in Prince George's County, MD, and our mailing address was Washington, DC and a zip. The current zip code map in the front of my Verizon yellow pages shows the zip code 20010 to be in an area of NW Washington DC bounded by Rock Creek Pkwy to the west, Quincy Street to the North, Park Place to the east, and Irving Street to the south. But, as someone has already mentioned, the zip code boundaries change over the years. Barbara