Why Does the Census Matter?

Why Does the Census Matter?

The U.S. census, one of the few in the world to directly count every resident, is used to distribute political power and federal funding. The 2020 count has faced pandemic-related complications and a suite of controversies.
An aerial view of a Los Angeles neighborhood in the evening.
An aerial view of a Los Angeles neighborhood in the evening. Shabdro Photo/Getty Images
  • The U.S. census is a direct count of every resident. Required by the Constitution, it has taken place every decade since 1790.
  • The data it collects is used to determine political representation in Congress and to direct more than $1.5 trillion in federal funding annually.
  • Following pandemic-related delays and controversies around the 2020 census, the Census Bureau has begun releasing the results. The first set of data shows low population growth and a shift of seven congressional seats.


The U.S. census, established by the U.S. Constitution, has played a major role in the country’s democracy since its founding. Conducted every ten years, it provides detailed data on the U.S. population—the world’s third largest—that is used to distribute political power and direct more than $1.5 trillion in federal spending each year. It has also been at the center of national controversies around slavery, immigration, congressional redistricting, and racial discrimination.

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The 2020 census faced scrutiny over President Donald Trump’s attempts to add a question about citizenship status and to exclude undocumented people from apportionment figures, as well as criticism over rising costs and vulnerability to cyberattacks. Additionally, the COVID-19 pandemic disrupted census procedures and escalated fears of an inaccurate count. After a monthslong delay, early results of the count have been released, showing U.S. population growth dropped to a near record low. In addition, seven congressional seats will shift to southern and western states.

What is the census and why does it matter?

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The U.S. census, undertaken every ten years, is a direct count of the total number of U.S. residents, including citizens, legal residents, long-term visitors, and undocumented immigrants. The census compiles biographical data on the U.S. population, logging characteristics such as age, sex, and race.

This data is used for several purposes, most prominently for reapportioning political power. It is the basis for distributing seats in the House of Representatives and in various state legislatures. Census findings also help determine the number of Electoral College votes for each state, which are used to elect the president.

Additionally, it is used to distribute more than $1.5 trillion [PDF] annually for federally funded programs, which are apportioned based on an area’s population, age, and other factors. These programs include Medicaid, Medicare, food stamps, Section 8 housing vouchers, Pell Grants for students, and highway construction and maintenance. Private firms also use census data to identify potential investment opportunities or target new customers.

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What are the origins of the census?

The U.S. census is not a new phenomenon; it is required by Article 1, Section 2, of the Constitution, which states that [PDF] an “actual enumeration” of the population must take place every ten years. This has happened every decade since 1790.

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The country’s founders believed a national census was necessary to prevent the federal government from arbitrarily levying taxes and to keep individual states from inflating their population estimates to get greater representation in the House of Representatives. 

Censuses had taken place throughout history, including in China, Egypt, medieval England, and the Roman Empire. But experts say the United States was the first country to use a census to distribute political representation as the basis for its democracy. The U.S. census was also unusual because of the constitutional requirement that it be an “actual enumeration” of the population, as opposed to a rough estimate.

How is it carried out?

Though the census dates back to the country’s founding, the U.S. Census Bureau did not become a permanent agency until 1902. Today, the bureau is part of the Department of Commerce and its director is appointed by the president and confirmed by the Senate.

Conducting the 2020 census required counting some 330 million people spread across more than 140 million housing units. Researchers had to create a list of every residence in the country, and the federal government had to hire hundreds of thousands of temporary personnel. (This workforce reached 564,000 in 2010.) With mounting pressure to control costs—the price tag for the 2020 count is expected to reach about $15.6 billion through 2023, up from $13 billion in 2010—the bureau turned to aerial imagery and other technologies to reduce the need to send workers door to door and limit temporary hires.

Conducting the 2020 census required counting some 330 million people spread across more than 140 million housing units.

To further reduce costs, the bureau for the first time invited most households to fill out their census forms online. Households deemed less likely to respond online received paper questionnaires. Residents could also complete the census by phone. For those who didn’t respond, census takers followed up over the phone or in person. They similarly hand-delivered forms to households that were unable to receive mail at their physical address, and conducted face-to-face counts for certain communities, including people living in hotels and other transitory circumstances

How has COVID-19 affected the 2020 count?

As the new coronavirus gained hold in the United States, the bureau delayed or extended most phases of the census, temporarily reduced staff, and suspended field operations. The virus also prompted officials to cancel job fairs used to recruit census takers, and forced organizations to scrap in-person community awareness activities. 

In April 2020, the Census Bureau asked Congress to extend its deadlines, a request that was not granted. Following several timeline changes, the agency concluded counting people in mid-October 2020. It released the apportionment numbers nearly four months behind schedule, in April 2021, missing the legally mandated, end-of-year deadline for the first time since it was imposed in 1976. 

What have been the controversies?

Disputes over apportionment, demographics, and accuracy have cropped up since the beginning. For the 1790 census, U.S. marshals traversed the country on horseback to count each household and ask residents six demographic questions, including age, sex, and number of slaves owned. However, several early leaders, including President George Washington and Secretary of State Thomas Jefferson, doubted the official population count of just under four million, believing the true number to be higher.

Another early controversy revolved around slavery. At the Constitutional Convention, southern states argued for slaves to be counted, which would increase those states’ representation in Congress, while northern states opposed it. This was resolved in 1787 by the three-fifths compromise, under which slaves would count on the census as three-fifths of a person. The practice endured until the Fourteenth Amendment, ratified in 1868, established that all people, including freed slaves, would be fully counted.

The rise of cities caused additional tensions. When the 1920 census found that, for the first time in U.S. history, a majority of residents lived in urban areas, many members of Congress from rural areas worried that new districts would eliminate their seats. As a result, Congress decided not to pass a reapportionment law for a decade, ensuring that urban areas were underrepresented until after the 1930 census.

Questions about race or ethnicity have long been contentious, with critics citing their potential for discrimination. Congress used the 1890 census data on race to set immigration quotas in 1924, hoping, in the words of a Census Bureau director, to keep out “beaten men from beaten races”—a reference to high immigration rates from Southern and Eastern Europe. During World War II, the 1940 census data was used to detain roughly 120,000 Japanese Americans for internment camps, something census officials denied for decades.

In recent years, the bureau has changed its approach to asking about identity. Beginning in 1970, the census asked residents if they were of Hispanic origin. In 1990, the census added an “unmarried partner” category, which was used to estimate the number of same-sex couples, though until 2020 it did not ask whether partners were of the same sex or opposite sex.

What have been the debates over the 2020 census?

President Trump in 2018 announced plans to add a question about citizenship status to the short-form questionnaire every household answers, a practice abandoned since 1950. The administration argued that the change would help enforce the 1965 Voting Rights Act by achieving a more accurate count of eligible voters. However, critics alleged that it was instead intended to pressure millions of noncitizens to avoid filling out the census.

The issue went to the Supreme Court, which ruled against the Trump administration in June 2019. Still, the administration pressed ahead with efforts to get citizenship data from other federal and state agencies. In July 2020, Trump issued a memorandum calling for the exclusion of undocumented immigrants from apportionment counts, arguing that giving them congressional representation would undermine democratic principles. Statisticians and legal experts decried the mandate as infeasible and unconstitutional, but the Supreme Court threw out a case challenging it. On his first day in office, President Joe Biden signed an executive order rescinding Trump’s efforts to obtain citizenship data from non-census sources and to leave undocumented immigrants out of apportionment counts.

Other recent controversies center on the 2020 census’s treatment of race and ethnicity. The Barack Obama administration had proposed more granular accounting of those with Hispanic, Middle Eastern, or North African origins, which it argued would improve accuracy, but the Trump administration rejected the changes.

At the same time, concerns about cybersecurity have risen. Before the 2020 count, some cybersecurity specialists expressed alarm [PDF] that the Census Bureau’s electronic data was not adequately safeguarded. The first-ever use of smartphone apps to record this data added to such fears. A U.S. government watchdog warned that, as of January 2021, the agency had not fully addressed the group’s advice on bolstering cybersecurity.

Many observers have raised additional concerns that pandemic-related disruptions and other factors diminished the census’s accuracy. Hurricanes in southeastern states and wildfires on the West Coast, as well as public unrest, added to the challenges. Under pressure, the agency reportedly cut corners, including by telling census takers to make guesses when recording data. The Census Bureau says it counted nearly all households, but observers have cast doubt on the totals. An independent audit by researchers from the American Statistical Association is ongoing.

What are the results of the 2020 census?

The Census Bureau released the first set of results in April 2021, finding that there were 331,449,281 U.S. residents. It also showed a population increase of 7.4 percent since the 2010 census, the second-lowest growth rate in U.S. history (behind only the 1930s). An aging population is largely the cause of the lower rate, experts say, but a decrease in immigration, the pandemic, and the Great Recession could also have played roles.

Three states—Illinois, Mississippi, and West Virginia—and the territory of Puerto Rico lost residents in the 2010s, and the overall population shifted toward the Sun Belt region, where 62 percent of U.S. residents now live. The results will reshuffle states’ representation in Congress and in the Electoral College, giving more political power to states in the country’s south and west.  Seven seats in the House of Representatives will change states. 

This reapportionment is more modest than many experts anticipated, and narrow margins decided some of the changes. For example, New York lost a seat by fewer than one hundred people. California saw its first-ever loss of a representative.

The release of this data kicks off the redistricting process, though state authorities will need more detailed census information, which is expected late this summer, to redraw their voting maps. States could challenge the reapportionment of seats, as Massachusetts and Montana did following the 1990 census [PDF]. 

How does the U.S. census compare with those of other countries?

Most countries undertake some form of a census. According to the UN 2020 World Population and Housing Census Program, almost every country will hold a census between 2015 and 2024, what it calls the “2020 round.” Exceptions include war-torn countries such as Afghanistan, the Central African Republic, South Sudan, and Syria. This marks an increase from the 2000 round, when twenty-seven members did not hold a census. Some countries, including Brazil, have postponed or altered their census procedures due to the pandemic.

Redistributing political power. Like many representative democracies today, the United States uses census data to reapportion legislative seats. While the United States aims to make congressional districts of approximately equal population, some other countries take different approaches.

In India, the world’s largest democracy, a commission redraws the national parliamentary boundaries based on census results. This last happened in 2002, and is not set to occur again until after 2026. In Canada, electoral districts in the lower house, known as ridings, are redrawn after a decennial census. Unlike U.S. congressional districts, Canadian ridings can vary greatly in terms of population. They are drawn by independent commissions, in contrast with the U.S. practice of allowing partisan state legislators to redraw boundary lines to benefit their own party, a process known as gerrymandering. Even so, the Canadian system has led to complaints of malapportionment, or underrepresentation in areas where the population has grown rapidly in recent decades.

Malapportionment is also a problem in Japan, where the country’s rapidly shrinking population has led to voting districts that vary widely in size, with rural areas now overrepresented. By rule, the largest district in the upper house of the Japanese Diet should only contain up to three times as many people as the smallest, though that does not always happen. Electoral maps have become the subject of repeated court challenges in Japan, where censuses are held every five years.

Privacy and identity. In many countries, censuses have proven divisive over demographic questions. European countries in particular have faced public outcry over privacy concerns regarding census data. In Germany and elsewhere, memories linger of the weaponization of census data against Jews and other minorities during the Holocaust. To this day, Germany does not collect census data on race. In France, censuses have been barred from asking about race since 1978. An 1872 French law had already prohibited censuses from asking about religious beliefs.

Statistical methods. The United States differs from many countries in that it aims to count every individual. Some countries, such as Israel and the Netherlands, combine various administrative registries with statistical samples to estimate the national population. Others, such as France, use a so-called rolling census, polling different samples of the population over extended periods of time. An advantage of the U.S. approach is that it provides highly detailed data, down to the city-block level for a specific point in time, but a disadvantage is cost. With a final bill of $13 billion, the 2010 U.S. census cost $42 per person; the 2011 Dutch census cost roughly $1.6 million, or nine cents per person.

Security. Comparisons with other countries underscore potential new challenges for the U.S. Census Bureau as it moves toward more online data collection. For example, cybersecurity experts note that Australia’s first online census, in 2016, was disrupted by a distributed denial-of-service (DDoS) attack that originated overseas. It cost tens of millions of dollars to fix and might have undercut public confidence in the process. 

Recommended Resources

The Brookings Institution’s William H. Frey breaks down the first results from the 2020 census.

CNN explains what’s at stake if the 2020 census fails to count everyone.

Former U.S. Census Bureau Director John H. Thompson joined other experts to discuss the risks of getting the 2020 census wrong at this April 2019 CFR event.

For Foreign Affairs, Nicholas Eberstadt describes how the demographics of the United States, its allies, and its adversaries will shape the international order.

For media inquiries on this topic, please reach out to [email protected].

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