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 as well as federal funding. In 2020, it faces complications due to the coronavirus pandemic, as well as controversy over immigration, cybersecurity, and rising costs.
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 nearly $900 billion in federal funding.
  • It has been at the center of national controversies over slavery, immigration, and civil rights; the 2020 coronavirus pandemic presents a new suite of challenges.


The U.S. census, established by the 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 nearly $1 trillion in federal spending. 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, now underway, has faced scrutiny over President Donald J. Trump’s attempts to add a question about citizenship status, which opponents say would alienate immigrants and distort the count, and to exclude undocumented people from apportionment figures. The process has also faced criticism over rising costs and increasing vulnerability to cyberattacks. Meanwhile, the pandemic of a new coronavirus disease, COVID-19, that is sweeping across the United States is disrupting census procedures and raising fears of an inaccurate count.

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, marital status, race, income, education, and languages spoken at home.

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.

It is also used to determine the distribution of nearly $900 billion for federally funded programs, which are apportioned based on an area’s population, income, age, and other factors. These include some of the country’s largest spending programs, including 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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The last census, in 2010, found that there were 308,745,538 residents in the United States, a 9.7 percent increase from 2000. It also found that population growth was uneven among the states, reflecting an ongoing demographic shift away from the northern and midwestern Rust Belt of former manufacturing powerhouses and toward states in the southern Sun Belt. As a result, states such as Texas and Florida gained more representation in Congress and in the Electoral College, which elects presidents, while states such as New York and Ohio lost representatives.

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Experts at the nonpartisan Brennan Center for Justice anticipate that the 2020 census will result in an increase in congressional seats for Arizona, Colorado, Florida, Montana, North Carolina, Oregon, and Texas. Meanwhile, Alabama, Illinois, Michigan, New York, Ohio, Pennsylvania, Rhode Island, and West Virginia are all expected to lose seats.

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 U.S. Constitution, which states that [PDF] an “actual enumeration” of the population must take place every ten years. This has happened every decade since 1790.

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. James Madison said that census data would be something “all legislatures had wished for; but this kind of information had never been obtained in any country.”

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 statistical sample or other forms of roughly estimating a population.

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 census requires counting some 330 million people spread across more than 140 million housing units. Researchers must build a list of every single residence in the country, and the federal government must hire hundreds of thousands of temporary workers—that number reached 564,000 in 2010. With mounting pressure to control costs—the price tag for the 2020 budget is expected to surpass $15 billion, up from $13 billion in 2010—the bureau has turned to aerial imagery and other technologies to reduce the need to send workers door to door and limit the number of hires.

Conducting the census requires 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. Those invitations went out in March. Households deemed unlikely to respond online received paper questionnaires. Employees also hand-deliver letters to the 5 percent of households that are unable to receive mail. For those who don’t respond, the Census Bureau sends reminders before census-takers follow up in person.

How is the coronavirus affecting the 2020 count?

As the 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 for delivering apportionment counts and redistricting data by 120 days. It also began planning to collect data through October. But the bureau backtracked in August 2020, a decision its officials believe came from the Department of Commerce or the White House, announcing it would ratchet up operations to finish counting in September and meet its original reporting deadlines.

Responses are coming in, but many observers—including some within the Census Bureau—fear coronavirus-related disruptions and the truncated timeline will diminish the census’s accuracy. Census-takers only began visiting nonresponsive households in July 2020, months behind schedule, giving them a matter of weeks to finish their count. Hurricanes affecting southeastern states and wildfires on the West Coast add to the challenge. The Census Bureau also has less time to review the data before submitting it, which raises concerns about data quality.

Minority, immigrant, and rural populations could be undercounted, some experts say, while other groups could be overrepresented. The movement of people due to the pandemic, particularly by college students sent home from campus, could also affect federal funding distributions based on the count.

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 round up 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 included no specific questions on sexual orientation.

By 2000, as the country became increasingly diverse, people were permitted to select multiple categories on a question about racial identity. Yet, in the most recent census, 97 percent of the U.S. population said they identified with only one race. Those who selected only white made up the largest group, at 72 percent; those who said black or African American accounted for 13 percent, while those who said Asian accounted for 7 percent. More than 16 percent of respondents identified as being of Hispanic or Latino origin, which the census considers a separate concept from race.

What are 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 as many as nine million noncitizens to avoid filling out the census. These nonresponses, some experts say, would disproportionately affect counts in heavily Democratic states including California and New York, which would in turn decrease the size of their congressional delegations. It could also change the way districts get redrawn within states, shifting voting power to traditionally Republican areas. Some activists have long argued that undocumented residents, who number an estimated eleven million people, should not be counted for apportionment purposes.

The issue went to the Supreme Court, which ruled in June 2019 that the Voting Rights Act was not a credible reason to add a citizenship question. However, the Trump administration has 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, and a court blocked it for violating federal law.

Even if the Census Bureau cannot fulfill Trump’s directive, the shortened census schedule could ensure that undocumented immigrants and other groups go uncounted, which some critics argue is a deliberate attempt to sway the results in favor of Republicans. Experts raised similar concerns about politicization in June 2020 when the Trump administration created, and then filled, several new, high-level political positions in the Census Bureau. For now, a federal judge has ordered the bureau to continue field operations and pause its efforts to meet the condensed timeline.   

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, cybersecurity is a rising concern as the bureau moves many forms online in an attempt to increase response rates and reduce costs. Some cybersecurity specialists have expressed alarm [PDF] that the Census Bureau’s electronic data is not adequately safeguarded. The first-ever use of smartphone apps to record this data has added to such fears.

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.” The few exceptions include war-torn countries such as Afghanistan, the Central African Republic, South Sudan, and Syria. This marks a significant increase from the 2000 round, when twenty-seven members did not hold a census. Some countries, including Brazil, have postponed or altered their 2020 census procedures due to the pandemic.

Redistributing political power. Like many representative democracies today, the United States uses census data to reapportion legislative seats, and thus each round can give states and regions more or less political power. 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 the most recent census results. This last happened in 2002, and the next census will not occur 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 nonpartisan 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. U.S. Census Bureau officials have publicly warned that countries such as Russia could seek to interfere with the 2020 process or to hack into census databases.

Recommended Resources

The Brookings Institution’s William H. Frey argues that the Trump administration’s attempts to rush the census and exclude undocumented people will imperil the country’s future.

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

This Science article looks at whether the 2020 census numbers will be accurate enough.

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.

This CFR In Brief looks at who counts in the 2020 U.S. census.

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


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