Now that you have spent some time scanning the sheets of numerous ancestors in their 1940 hometown, you may have a few who lived in a larger town or city. That creates just too many pages of census records to cover.
So using the Steve Morse ‘One-Step Enumeration District’ finder online can assist you to narrow down that search. Of course once all the names from all the states and territories have been indexed, it will be simpler to locate an individual, just by using their given and surnames, but that will take months to accomplish. Until then, this one-step method can help.
Start by selecting a state, then a county name if you know it. If you don’t know the county, do put in the name of the city or town. For example, the city of Miami, Dade County, Florida was an average size city in 1940, not as populated as it would get by the 1960s and 1970s. Yet even then, just within the city of Miami there are still some 115 enumeration districts. If you know a more specific location rather than just saying Miami that the ancestor lived it would help narrow the search. For example there is Hialeah, Miami Shores, Coral Gables, North Miami or Opa-Locka to name a few; each with about five to 22 enumeration districts.
Once you have the location narrowed the Morse one-step finder will show you a link to each enumeration district just below the listing of state and county. Next you can have displayed census images for that district. It is best to start with the first one (they are numbered) and work through each. You can have the images displayed from the National Archives & Records Administration site, from Ancestry.com site or My Heritage.com viewer. Morse has placed all three conveniently there. A reminder, that Ancestry and My Heritage will have a limited time period where free access to the images is available, so the NARA is the best viewer.
Each district can be one to several pages in length, so scan each carefully for names. With the NARA viewer you can download any image you find of interest, which is a good approach, so you can have that image later to refer to. The Steve Morse finder is a great way to get started.
You do need to be patient when going over the census pages, it is easy to overlook a name, especially if there might be a different spelling than you were looking for. Also being handwritten, it can be hard to differentiate certain letters to know what is spelled.
As with any census, at any time period, or any document, there can be errors or false information provided. Never accept 100% the information for each ancestor on any census. Use it only as a guide. You will want to trace other sources to verify what is located. So far the ancestors I have located on the 1940 census, I have found errors in all the information relating to them.