12 Facts About the Census
Read a PDF of this factsheet here
- The U.S. Constitution requires that every person living in the country be counted in the census. Article 1 of the Constitution empowers the Congress to carry out an actual enumeration of the country’s population. That enumeration, or census, is the basis for determining how seats in Congress are divided among the states and how federal funding is distributed to communities. While the Census Bureau may use tools such as imputation and administrative records to address missing responses, these methods are designed to support — not replace — the constitutional requirement of a full count. Ensuring that every person is 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 citizens and noncitizens alike. 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 apportionment 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.
- 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 complete. It estimates undercounts (people missed) and overcounts (people counted more than once) to assess the net accuracy of the count. However, the 2020 PES was not designed to “correct” or revise the census numbers; the Census Act (Title 13, U.S.C.) 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.
- Funding for the census follows a cyclical pattern, ramping up over the course of the more than decade-long planning cycle. In the early years of each cycle, funding is primarily allocated to research, testing, developing improved methodologies, and evaluating emerging technologies. As the census date approaches, funding needs to 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, with some funding remaining for post-census evaluations and preparation for the next cycle. This funding cycle ensures that the Census Bureau can effectively plan and execute the count while adapting to a changing country and emerging technologies.
- A mid-decade census is neither required by the Constitution nor operationally possible to conduct. The Constitution mandates a nationwide census once every 10 years, and the Census Bureau’s operations are built around that timeline. Planning, testing, and deploying the decennial census is a decade-long effort that requires years of research, technology development, outreach, and staffing. Attempting to conduct a second national headcount in the middle of the cycle would be prohibitively expensive, duplicative of existing efforts, and operationally impossible to execute with accuracy. Instead, the American Community Survey already provides updated annual data on population and demographics between censuses, ensuring policymakers and communities have timely information without the disruption of an unscheduled national census.
- The American Community Survey (ACS) collects statutorily required demographic and socioeconomic data about the nation’s population. The ACS is an ongoing, monthly survey administered by the U.S. Census Bureau as part of the decennial census program that produces updated socioeconomic data every year about our population and communities. 3.5 million randomly selected 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 minimal 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. They are also required for implementation and enforcement of the Voting Rights Act.
- The census informs emergency preparedness and disaster response. Census data provide critical insights for emergency response planning, helping tribal and local governments identify populations 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 infrastructure. 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 help 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. The census is vital for tribal communities because it helps ensure adequate federal resources for essential services like health care, education, housing, and infrastructure; 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 secures fair political representation in local, state, and federal governments, ensuring tribal nations have a voice in policy decisions that impact their future.