The Census

Article I requires an actual enumeration of the population every ten years to apportion seats in the House. The first census, in 1790, was conducted by U.S. marshals under Secretary of State Thomas Jefferson and counted about 3.9 million people. The count is now run by the Census Bureau, part of the Commerce Department, and aims to count every person living in the country on Census Day, April 1, regardless of citizenship or legal status. The 2020 census counted 331,449,281 people.

The census decides how the 435 House seats and the electoral votes are divided among states, supplies the population data states use to redraw districts, and steers the distribution of more than two trillion dollars a year in federal funds through formulas based on population. Responding is required by law, and individual answers are kept confidential for 72 years, after which the records are released by the National Archives. Between decennial counts, the American Community Survey samples about three and a half million households a year for detailed data.

Every census involves disputes over accuracy and who should be counted. Each count misses some groups, including young children, renters, and some minority communities, and overcounts others. In Department of Commerce v. New York in 2019 the Supreme Court blocked a planned citizenship question for the 2020 census. Questions about excluding unauthorized immigrants from apportionment counts have resurfaced ahead of the 2030 census, which the Bureau is preparing to conduct largely online.