The first United States census took place in 1790, beginning on August 2 of that year.
The census was required by Article I of the Constitution, which directed the federal government to count the population for representation and direct taxation. Marshals of the United States conducted the enumeration, visiting households across the 13 states, along with the districts of Kentucky, Maine, and Vermont.
The official count recorded 3,929,214 people, including enslaved people. The census categories were limited by modern standards: free white males, free white females, other free persons, and enslaved people. Native Americans were generally excluded from the formal apportionment count.
The results determined the initial apportionment of seats in the House of Representatives. Pennsylvania had the largest population, followed by Virginia. The federal census has continued every ten years since 1790, making it one of the oldest recurring government data programs in the United States.