How many people did the first United States census count in 1790?

The first United States census counted 3,929,214 people in 1790.

The census was conducted under the constitutional requirement that population be counted every ten years. Marshals of the United States collected information between August 1790 and 1792, asking for household details rather than recording every modern category of demographic data.

The count covered the eleven states then participating in the federal government, along with the districts of Kentucky, Maine, and Vermont. It did not include territories such as the Northwest Territory in the same way as the states and listed districts.

The census divided the population into categories including free people and enslaved people. Its total was used to apportion seats in the House of Representatives. Later reviews found some undercounting, especially in frontier areas, but 3,929,214 remains the official published total for the first census.