Facts About the Census
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- Article I of the U.S. Constitution requires a count of every person living in the country every ten years. The census is the basis for determining how many seats each state gets in the U.S. House of Representatives and how federal funding is distributed to communities. While the Census Bureau may use statistical methods (such as imputation) and administrative records to fill in missing responses, these methods are designed to support — not replace — the constitutional requirement of a full count. Ensuring that all persons are counted where they live strengthens the accuracy of the data and upholds the fairness of representation and resource allocation.
- The U.S. Constitution mandates a census that counts all residents of the country, regardless of citizenship. The 14th Amendment to the Constitution requires a count of “the whole number of persons in each state” every 10 years for the purpose of apportioning seats in the U.S. House of Representatives. It does not distinguish between citizens, noncitizens, legal residents, voters, or undocumented persons. This inclusive vision gives us a true snapshot and understanding of our country and ensures that elected officials represent all residents and taxpayers.
- The Census Bureau is the only institution with the expertise, capacity, and authority to conduct an accurate count of the nation’s population. Congress established the Census Bureau with a constitutional mandate to conduct a full count of the nation’s population every ten years. The Census Bureau’s extensive experience in carrying out the census gives it the unique institutional knowledge and technical expertise necessary to conduct this massive operation. Proposals to deploy U.S. Postal Service workers to conduct the census have not stood up to scrutiny by the Government Accountability Office, with increased costs and significant mail service delays among the challenges. Instead, Congress must prioritize timely and sufficient resources for the Census Bureau to conduct a complete, fair and accurate census.
- The Census Bureau uses a Post-Enumeration Survey (PES) to evaluate the accuracy of the census. The PES is a statistically representative survey conducted independently after census data collection is finished. It estimates undercounts (people missed) and overcounts (people counted more than once) to assess the net accuracy of the count. However, the 2020 PES is not designed to “correct” or revise the census numbers; the Census Act (Title 13, U.S.C.) also prohibits the use of sampling for congressional apportionment. In addition, the PES only estimates the accuracy of the household count — it does not cover people living in group quarters (such as college dorms, prisons, or nursing homes) or Remote Alaska.
- There are census undercounts and overcounts in every state, in every census. There is simply no evidence that the Census Bureau has ever favored one state over another in conducting the census or tabulating the responses. While the Census Bureau works hard to reduce duplicate counts and undercounts everywhere, the involvement and investment of state and local governments in promoting census participation play a key role in achieving a full and accurate population count. These efforts are critical in helping to address specific local challenges and to ensure proper representation for all communities.
- Differential privacy does not affect the state population totals used to reapportion seats in the House of Representatives. Differential privacy is a statistical technique used to protect against the disclosure of confidential information about every person and household counted in the census, as federal law requires. Differential privacy is a mathematical framework for adding carefully calibrated amounts of random statistical “noise” (i.e., imprecision) to published statistics, so that no one’s information can be singled out and, possibly, misused. Moreover, state population totals (which are used for reapportionment) are published without the injection of any statistical noise.
- A mid-decade census is unnecessary, prohibitively expensive, operationally difficult, and cannot be used to reapportion U.S. House seats or for congressional redistricting. The Constitution mandates a nationwide census once every 10 years for apportionment purposes. Current law permits a mid-decade census only in the year ending in “5” (i.e., 2025, 2035, etc.), and only for the purpose of producing updated demographic and socioeconomic data; the law prohibits using mid-decade census data to reapportion seats in the U.S. House or for redistricting. It is neither legal nor operationally feasible for the Census Bureau to conduct a “new” census to update 2020 Census data at this point in the decade. In fact, the Census Bureau has never actually conducted a mid-decade census, likely because the effort would be so time consuming and costly. Instead, with Congress’ blessing, the Census Bureau launched the American Community Survey (ACS) in 2005. This ongoing part of the census already provides updated annual demographic and economic data to support policymaking and resource allocation, making a mid-decade census unnecessary and duplicative.
- The American Community Survey (ACS) collects detailed demographic and socioeconomic data required to implement federal laws. The ACS is an ongoing, monthly survey administered by the U.S. Census Bureau as part of the decennial census program that produces updated statistics every year about our population and communities. 3.5 million housing units receive the ACS annually in the United States, including Puerto Rico. Every question on the American Community Survey collects data required by law to implement, monitor, or enforce specific federal government programs and policies. State, local, and tribal governments, business and industry, philanthropy, and nonprofit organizations also rely extensively on ACS data to guide their activities. The Paperwork Reduction Act ensures that the burden on ACS respondents is as low as possible.
- The ACS includes a question about citizenship status. ACS citizenship and national origin data help government and communities understand demographic change; enforce laws, regulations, and policies against discrimination based on national origin; and plan for the educational needs of students. The data are also required to implement and enforce the Voting Rights Act.
- Race and ethnicity data collected in the census and American Community Survey help ensure fairness and strengthen the U.S. economy. These data are necessary to implement civil rights laws and ensure equal opportunity for all Americans. Race and ethnicity data give businesses market insights to grow and compete and help local governments target services more efficiently. These data are not used to allocate federal funding. Starting with the 2027 ACS, the Census Bureau will implement updated federal race and ethnicity categories in all of its surveys, including the 2030 Census. The modernized categories reflect more than two decades of objective, comprehensive scientific research and engagement with knowledgeable stakeholders and policymakers, and will produce a more accurate portrait of the nation’s population.
- Funding for the census follows a cyclical pattern, ramping up over the course of a decade-long planning cycle. In the early years of each decade, funding is primarily allocated to research, testing, developing more accurate counting and outreach methods, and evaluating emerging technologies. As the census year approaches, funding must increase significantly to support nationwide infrastructure deployment, outreach and promotion, data collection, and field operations. After data collection ends, the focus shifts to data processing and reporting, and post-census evaluations. This funding cycle ensures that the Census Bureau can effectively plan and execute the count while adapting to a changing country and leveraging new technologies.
- The census informs emergency preparedness and disaster response. Census data provide critical insights for emergency response planning, helping tribal and local governments identify communities most vulnerable to disasters like hurricanes, wildfires, or pandemics. Accurate population and housing information allows for better allocation of resources — such as food, medical supplies, and temporary shelters — during emergencies. For example, ACS data guide evacuation planning and recovery efforts to prioritize areas with the greatest need.
- The census guides economic development and business planning. Businesses rely on census data to make informed decisions about where to open new stores, build offices and factories, and invest in workforce training. The data provide critical insights into population growth and composition, income levels, and workforce availability, fostering economic development and job creation in all communities.
- Census data are required to monitor civil rights compliance. Census data are crucial for enforcing civil rights laws, such as the Voting Rights Act and the Fair Housing Act. Information about race, ethnicity, and housing patterns helps identify and address discrimination and ensure equal access to opportunities.
- The census plays a crucial role in the well-being of tribal communities. An accurate census is vital for tribal communities because it helps ensure adequate federal resources for essential services like education and housing; supports tribal sovereignty by enabling advocacy for resources based on population size; helps address health disparities through programs like the Indian Health Service; informs infrastructure planning for critical needs such as water and transportation; and guides fair political representation in local, state, and federal governments, ensuring Tribal Nations have a voice in policy decisions that affect their future.