In researching family genealogies I've discovered the valuable uses of censuses. But in the 19th century there were very new. The first census in the U.S. was in 1790.
2nd 1800 It counted Men under 10, M10 & Under 16, M 16 & under 26, M 26 & Under 45, M 45 & up as well as the same for Females. It also listed the Names of Heads of families
7th 1850 This census marked a change they attempted to count every member of the household including women, children & slaves.
8th 1860 This census counted American Indians
10th 1880 This census allowed women to be enumerators.
11th 1890 Announced that the frontier region of the U.S. no longer existed. So, it was no longer needed to track westward migration. This census was also notable for the use of the tabulating machine, reducing the time to tabulate the census from 7 years to 2.5.