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What Is the Census?

The U.S. Constitution mandates a census every ten years to count every person living in the United States, and this count plays a key role in determining political representation and allocating federal resources.

  • Alexis Farmer
Published: March 26, 2018


The U.S. Consti­tu­tion (Article I, Section 2) mandates a census every ten years to count every person living in the United States. The first census took place in 1790. Since 1930, Census Day has occurred on April 1 every decade; the next Census Day is April 1, 2020.

The census plays a key role in determ­in­ing polit­ical repres­ent­a­tion and alloc­at­ing federal resources. Census data is used to determ­ine how many congres­sional seats each state receives during the once-a-decade reap­por­tion­ment process. State legis­lat­ors and local govern­ments also rely on census data for redis­trict­ing, where the data ensures that districts are equally popu­lated and helps guide decisions on whether to draw major­ity-minor­ity districts. The federal govern­ment, like­wise, uses popu­la­tion totals to determ­ine how much fund­ing cities and states receive for things like educa­tion, health care, and the arts. Busi­nesses also use census data to guide their decisions on invest­ment, market­ing, and advert­ising.

The census form asks one person from each resid­ence to answer a uniform set of ques­tions about the people who live or stay in the resid­ence. For example, the 2010 census included ques­tions about the number of people who lived in a house­hold, their age, sex, and race, and how they were related to the person complet­ing the form. The form also reques­ted inform­a­tion on the owner­ship of the hous­ing unit and asks whether people living in the house­holds were of Hispanic, Latino, or Span­ish origin. Previ­ous censuses have asked about educa­tional attain­ment levels, home finan­cing, and marital status. But those ques­tions have been replaced in recent years with a longer, separ­ate survey known as the Amer­ican Community Survey (ACS). The ACS is conduc­ted every year to provide up-to-date inform­a­tion on demo­graphic, social, and economic char­ac­ter­ist­ics of our nation’s communit­ies. The ACS is sent to a small percent­age of house­holds on a rotat­ing basis through­out the decade.

Tradi­tion­ally, the census form has been a paper ques­tion­naire sent to every house­hold in the coun­try. However, the 2020 Census will, for the first time, give people the option to complete their ques­tion­naire online. Respond­ents will still be able to fill out a paper ques­tion­naire if they choose. They will also be able to give their responses over the phone.

Every house­hold is required to complete the census. Title 13 of the U.S. Code provides that anyone over the age of eight­een who refuses to answer census ques­tions could be fined up to $5,000. The Census Bureau is required by law to keep confid­en­tial all inform­a­tion that it collects from indi­vidu­als. No one except census work­ers may see a completed census form. A census employee could be fined or imprisoned for disclos­ing any answers from these forms.

The Consti­tu­tion charges Congress with the respons­ib­il­ity of conduct­ing the census. Congress has since deleg­ated that author­ity to the Census Bureau, which oper­ates under the Depart­ment of Commerce. The U.S. Senate Commit­tee on Home­land Secur­ity and Govern­mental Affairs and the Govern­ment Oper­a­tions subcom­mit­tee of the U.S. House Commit­tee on Over­sight and Govern­ment Reform over­see the Census Bureau. The Census Bureau is led by a director and deputy director, who are typic­ally career civil servants with exper­i­ence with stat­ist­ical data collec­tion and analysis. The Pres­id­ent appoints the director, as required by federal law, subject to Senate confirm­a­tion. The deputy director does not require Senate confirm­a­tion.

The Census is an expens­ive under­tak­ing. Since 1960, the cost of census activ­it­ies has escal­ated. The 2010 census was the cost­li­est in U.S. history at about $12.3 billion, and the 2020 Census—if fully funded—is expec­ted to exceed that amount.

As all this suggests, the census is a crit­ical under­pin­ning of our demo­cratic systems. As tech­no­logy devel­ops and our nation’s popu­la­tion contin­ues to grow and diver­sify, the Census Bureau will continu­ally face chal­lenges to evolve and innov­ate. Now, and into the future, it must meet these chal­lenges while ensur­ing that every­one is fairly and accur­ately coun­ted.