The National Archives of the United States, in regard to the 1950 census, has posted a number of videos that are basic mini classes to help you understand that census. You can ask the archivists at the map room, they may be able to help you research using their historical maps to help you locate other places in time.
Excerpt:
A census enumeration district was an area that could be covered by a single enumerator, or census taker, in one census period. Enumeration districts varied in size from several city blocks in densely populated urban areas to an entire county in sparsely populated rural areas. This presentation will focus on locating and using census enumeration district maps, with an emphasis on maps from the 1950 census.
