As shown above, these are favorites because of the specific questions asked during those two Census years. The answers that ancestors gave were clues to further researching their lives. Here are just two examples.
1900 US Census Clues: Farkas Family
As enumerated in the 1900 Census, my maternal great-grandfather Moritz "Morris" Farkas (1857-1936) was a boarder in the household of a Roth cousin. His birth year is shown as 1857. The month is not indicated (it's omitted from many on this page).
Thanks to this Census hint about birth year, I went looking for Moritz's birth in the Hungarian records a few years ago. At the time, I had to request FHL microfilm #642919 of Jewish records gathered at Fehergyarmat, Hungary. Very exciting to find him there (as "Moses Farkas") after two hours of cranking the microfilm reader at a nearby Family History Center!
1910 US Census Clues: McClure Family
Here's the 1910 Census for my husband's great-great uncle Train Caldwell McClure (1843-1934). Look way over to the right on this record and you'll see "UA" in the column reserved for recording veterans. UA = Union Army!
I searched for and found his Civil War service in Company A of the 89th Indiana Infantry. Train entered the Union Army on August 3, 1862, and was mustered out nearly three years later on July 19, 1865 at Mobile, AL, according to the Report of the Adjutant General of the State of Indiana.
But in April of 2022, I'll have a new favorite: The 1950 U.S. Census, which will be released that year with a lot of detailed information about my ancestors. I can't wait!