What is the census used for?

The census is used to determine how many House seats each state gets, how electoral votes are allocated, and how more than 1.5 trillion dollars per year in federal funding is distributed to states and localities. The U.S. Constitution requires the census in Article I, Section 2 specifically for the purpose of apportioning seats in the House of Representatives among the states based on population. Every ten years, the 435 House seats are reallocated. Reapportionment rewards states whose share of the national population is rising and reduces the delegations of states whose share is falling. After the 2020 census, Texas gained two House seats, while California, Illinois, Michigan, New York, Ohio, Pennsylvania, and West Virginia each lost one.

Within each state, congressional district boundaries must then be redrawn to reflect the new number of seats and population shifts within the state. Census results also reshape the Electoral College for the next decade. Each state's number of electoral votes equals its number of representatives plus its two senators. States that gain House seats also gain electoral votes. The 2020 census changes affected the 2024 presidential election, the 2028 election, and the 2032 election before the next reapportionment based on the 2030 census.

The federal government uses census data to allocate more than 1.5 trillion dollars per year through hundreds of federal programs. Major programs that distribute funds based partly on census data include Medicaid, Medicare, the Supplemental Nutrition Assistance Program, federal highway funds, federal education funds (including Title I for low-income school districts and special education funding), public housing funds, community development grants, transportation grants, and many others. States and communities that are undercounted in the census receive less federal funding for the next decade, which is why ensuring an accurate count is so important.

State and local governments use census data extensively for planning roads, schools, hospitals, social services, public safety, and emergency response. Local governments use detailed neighborhood-level census data to plan zoning, economic development, and infrastructure investments. Businesses use census data for market research, deciding where to locate stores, and product planning. Researchers, journalists, and policy analysts use census data for academic studies, news reporting, and policy evaluation. The Census Bureau also conducts the American Community Survey, a continuous survey of a smaller sample of households that provides more detailed demographic and economic information than the decennial census, including data on income, education, housing, employment, and many other topics.