While I didn't solve any of my own mysteries, I had an opportunity to use the 1940 census to solve a mystery for a client from France for whom I had been doing research. While many of her family members perished in the Holocaust, this branch managed to exit the country in the early 1900s. She knew they had come to Minneapolis in 1910 and asked me to follow the trail. I had traced the family in the 1920 and 1930 census, reviewed birth and death records and located the naturalization record which confirmed that the father had arrived via Canada. I then went to the stacks of the Minneapolis Public Library which has the original city directories and traced the family through each year. The oldest son disappeared from the listings during the war years and I assumed he was away in the service. When I got to 1946 the family disappeared from the city, another mystery to be solved. Ah, but I had found my critical piece of information for the next step. The 1940 directory confirmed the address of the parents as well as that of the oldest son. Armed with the addresses I went to stevemorse.org.
For those unfamiliar with stevemorse.org, Steve Morse, the original architect of the Intel 8086, brought his expertise in computer science to build a better front-end search engine to many genealogy databases. His contribution to genealogy is immeasurable and continues to grow as he takes on new puzzles and challenges. If you go to his site and page down to US Census you will see an entry titled Unified 1940 Census ED Finder. Because the census is not yet indexed by name, it is necessary to first locate the address and then the enumeration district and this site will help you to do so.
Morse makes it simple to search if you have the address. After you enter it, the site will bring up a map. By entering the streets which surround the location you will narrow it down to the correct enumeration district. When you click on that district it will bring up between 30 to 40 pages which you now need to peruse to find the address. The street is noted on the left so a quick glance will allow you to page through until you find the address.
In the case I was researching I was able to find the original immigrants as well as their oldest son. When we last located them in 1930 they had one daughter. Daughters are always challenging to search on because they have that pesky habit of changing their name. Since 1930 they had added two sons to the family, one in 1932 and one in 1934. When I shared that information with my client she quickly did a search on one of the sons and found the great-grandson to our original immigrants on the Geni site. He had outlined his father’s family and it was a match! Now she has reached out to her living relatives, following the trail of the original Russian immigrants and connecting their descendants from France and the United States.