A. Enumeration districts (EDs)were administrative divisions of a county or township for the purpose of conducting the census. Before today’s online census indexes—and when the 1940 enumeration was first released in April 2012, but not yet indexed—you’d use the ED to identify the roll of census microfilm listing your ancestor’s household. Just as the underlying geography changed over the 10-year span between federal censuses, so too the EDs were redrawn.
Any 1950 ED maps probably won’t be put online until we get closer to the release of that census in 2022 (after the 72-year privacy period expires). Boundary descriptions of the 1950 EDs, but not the maps, are on National Archives microfilm publication T1224, which describes EDs for 1830 through 1890 and 1910 through 1950.
Local public and academic libraries may have 1950 ED maps, so it’s worth checking the catalogs of repositories in areas of interest. The University of Chicago library, for example, has six ED maps from the 1950 census.