The first United States census, conducted in 1790, recorded a total population of 3,929,214.
Congress directed the census under Article I of the Constitution, which required an enumeration for apportioning representation in the House of Representatives. Marshals conducted the count in 1790, beginning in August, across the fifteen states and several territories then included in the federal system.
The census counted free people, enslaved people, and other categories under rules that reflected the period's legal and racial classifications. Each enslaved person was counted as three-fifths of a person for congressional apportionment and direct taxation under the constitutional compromise, although the census also recorded enslaved people separately.
The final total excluded some Native Americans outside the tax system and was revised slightly after later review in certain jurisdictions. The 1790 census is therefore both a population benchmark and an important record of how the early republic measured representation. Philadelphia was the largest city, with 42,520 inhabitants.