Without the ability to use normal search engines, at this point, for locating family in the 1940 Census, I found that having relatively good Citations really helped me find folks in these images that can be scanned. I knew where to look.
I posted a number of posts on my genealogy database management software:
I was able to use my 1930 Data, to locate the Enumeration District for the 1940 Census. Using the Steve Morse Unified 1940 Census Tool, the identification was easy.
I used the Residence Fact for this tool. As you can see, I generated a printout, by Location, and the residence fact included the Enumeration District NUMBER so I could easily mark this page when I looked at the 1940 Census Tool. That is where I started. Who knew, who might have moved.
The Citation information, would verify for me, the ED #, Page Number, and Line Number from the 1930 Census.
That first entries Citation looks like this:
1930 U.S. census, Chester county, Pennsylvania, population schedule, enumeration district (ED) 3, page 1-A (stamped), lines 8 to 11, Birmingham, Wilmington Pike – Family 3, John Marshall Highley, digital image, Ancestry.com Operations, Inc, (http://www.ancestry.com, 12 April 2012), NARA microfilm publication T626, roll 2019, Image: 34.0; FHL microfilm: 2341753
Within my genealogy database software, I can easily see the 1930 Census image, if I need to look at the image. For example, to verify who might have been in the household in 1930, but not in 1940.
Finding the image for 1940 may have taken a few minutes, but I had a very good start.
Here is the Citation for this person in the 1940 Census.
1940 U.S. census, Chester county, Pennsylvania, population schedule, enumeration district (ED) 15-3, page 3-A (stamped), Birmingham, lines 31 to 34, family 49, J Marshall Highly; digital image, Archives.gov (http://1940census.archives.gov: accessed 04/06/2012); citing NARA microfilm publication T627, roll 3467
So, when the 1950 census comes around, I have a great starting point.
Lesson Learned: I had always considered a Citation useful for Others to see or find what I found, IF they looked at my research. Working in the scanning of Image for 1940 taught me that a good citation is more useful for ME.