Happy 226th birthday!
One of the most valuable tools for US genealogists is the National Census that is enumerated (created) every ten years. Census results were never intended to benefit genealogists. That is simply a side benefit. The primary purpose is to reapportion seats in the House of Representatives and to to realign congressional districts. Over the years, the Census numbers also have become important for the formulas that distribute hundreds of billions of dollars in federal funds each year.
The first national census took place on August 2, 1790, when marshals under the direction of Secretary of State Thomas Jefferson canvased the original 13 states plus Maine, Vermont, Kentucky, and the Southwest Territory (Tennessee). They asked six questions: name of the head of the household, and number of persons in each household in these categories: free white males over 16; free white males under 16; free white females; all other free persons; and slaves.
A total of 3,929,214 were counted. Compare that to 2010, when the count was 308,745,538. In what would become a decennial dissatisfaction, not everyone was happy with that very first count; both President George Washington and Secretary Jefferson expressed skepticism about the total, believing it was too low.
For anyone interested in the history and the impact of the cCensus, the US Census Bureau has created a web site where you can learn about legislation related to the censuses, the efforts to improve the count, and the technical innovations introduced to improve data collection, processing, and publication. You can start at https://www.census.gov/history/www/through_the_decades/.
The web site even includes complete Census Instructions for each decennial census. When the information recorded about your ancestor doesn’t make sense or seems to possibly be in error, a quick look at the Census Instructions will clear the mystery. Census instructions may be found at https://www.census.gov/history/www/through_the_decades/census_instructions/.