The first United States census counted 3,929,214 people in 1790.
The census was conducted under Article I of the Constitution, which required a population count for congressional representation and direct-tax apportionment. Marshals collected information from households in the newly formed states and districts, and the results were reported to President George Washington.
The count included free people, enslaved people, and other categories defined by the census law. It did not use modern demographic methods, and historians have found that some people were missed. The reported total therefore represents the official enumeration rather than a perfectly complete population measurement.
The 1790 census covered the original states plus the districts of Kentucky, Maine, and Vermont in the political geography of the time. It created the baseline for a census taken every ten years, a practice that continues in the United States and influences representation and federal planning.