1708 F Street, NW
For fun I decided to Google map the Milligan address of 1708 F Street, NW. I am not sure what F Street, NW looked like in 1943 but I was surprised at the location. The FBI wasn't talking to Joe Carter because they thought he was looking at the Government Printing Office, he was basically right across the street from the then State, War & Navy building. Today, it is the Eisenhower Executive Office Building which attaches to the West Wing of the White House.
Location, Location, Location. 1708 F Street, NW would have been a very good place to live for someone working in Washington, DC in 1943.