About which number was the population of the u. s. when congress took the first national census?

In the First Census, the population of the United States was enumerated to be 3,929,214.

The six inquiries in 1790 called for the name of the head of the family and the number of persons in each household of the following descriptions:

•Free White males of 16 years and upward (to assess the country's industrial and military potential)

•Free White males under 16 years

•Free White females

•All other free persons

•Slaves

Under the general direction of Thomas Jefferson, the Secretary of State, marshals took the census in the original 13 States, plus the districts of Kentucky, Maine, and Vermont, and the Southwest Territory (Tennessee).