Your questions about the 2020 Census, answered

Two children hold signs through a car window that reference the 2020 Census at a June outreach event in Dallas. (Tony Gutierrez/AP)
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On Thursday, the Census Bureau is scheduled to share its once-in-a-decade update of redistricting data. The second major release from the 2020 Census, it will provide a detailed look at demographic changes across the United States over the past decade, down to the neighborhood level.

Here are the top questions readers are asking about it:

Q: How will the 2020 Census affect my representation in Congress?

A: The number of seats in the House of Representatives — currently 435 — is set by law, but the number of House seats allocated to each state is adjusted every 10 years based on the decennial census’s updated state population totals. Some states gain seats, some lose them. Population growth is no guarantee a state will get another seat if other states added more residents. Each state gets at least one representative, regardless of population size. Based on the latest state population totals released in April, California, Illinois, New York, Michigan, Ohio, Pennsylvania and West Virginia all lost a House seat. Colorado, Florida, Montana, North Carolina and Oregon each gained one, while Texas gained two.

Q: Will my state use the 2020 Census to redraw voting districts?

A: That will depend on a number of factors this year. Each state has its own laws and timelines for redistricting. Release of the 2020 Census redistricting data was delayed because of the coronavirus pandemic, from April to August — too late for the legally mandated deadline for redistricting in some states.

Q: What is differential privacy, and how will it affect census data?

A: Differential privacy is a system the Census Bureau is using for the first time on the decennial census to protect responders’ personal information. In entails adding “noise” to the data to block potential hackers from using it to identify people.

Some experts say differential privacy may compromise accuracy. A May report from IPUMS, a survey data processing and dissemination organization at the University of Minnesota, found “major discrepancies” in data for minority populations.

Sixteen states have joined a lawsuit filed by Alabama against the Census Bureau, challenging the bureau’s plans to use differential privacy.

Q: Are there concerns about undercounts of minority populations in the 2020 Census?

A: Yes. The count ended in mid-October, two weeks earlier than the Census Bureau had planned, after the Supreme Court upheld a Trump administration order moving up the end date. The president wanted the numbers sooner as part of a push to exclude undocumented immigrants from being counted for House seats before he left office. Some enumerators — people who collect data for the census — reported that supervisors ordered them to cut corners or falsify data to meet the target threshold of 99 percent households counted. In a Nov. 5 post on its website, Deputy Director Ron Jarmin said it was “premature to definitively describe the quality of the 2020 Census or assess its fitness for use” and that “we’ve not uncovered anything so far that would suggest that the 2020 Census will not be fit for its constitutional and statutory purposes.” Minority populations are traditionally harder to count, as are low-income people, renters, children and immigrants.

Q: Why were the census results delayed?

A: The coronavirus pandemic froze the count just as it was getting started, leading the bureau to request a several months’ delay to conduct and analyze the census. Congress did not move on the request, and the bureau reverted to its original schedule for delivering state population totals to the president after then-President Donald Trump announced he wanted to exclude undocumented immigrants from being counted for apportionment. During ensuing legal battles, the end date was in flux, causing confusion among enumerators and their supervisors as they tried to complete the count.

Q: What happened to the citizenship question?

A: Soon after Trump took office in 2017, administration officials began discussing the addition of a citizenship question to the census, and they officially announced it in 2018.

Civil rights groups and experts inside and outside the bureau warned the question would probably depress participation in immigrant communities and lead to an inaccurate count, and multiple lawsuits challenged it. The Supreme Court blocked it in 2019, though Trump ordered federal agencies to share administrative records data on citizenship with the Commerce Department anyway. That effort ultimately failed — experts say it is impossible to ascertain how many undocumented immigrants reside in each state — and President Biden officially ended the effort shortly after he was sworn in.

Q: Can we redo the census? Why wouldn’t the government redo it after the problems it had during collection?

A: Yes, Congress can ask for a do-over. But it’s a massive undertaking that takes years of planning. It is also a costly one. A Government Accountability Office report released in June estimated the cost of the 2020 Census at around $14.2 billion.

Q: Is the 2020 Census going to be less accurate this year compared with previous ones? Can we consider the results valid?

A: This is an open question, although there will be different ways of assessing the quality of the data once the numbers come out. Census officials and outside experts will compare them to estimates and other sources. The bureau also conducts its own quality reviews, including going back to some of the households it counted and double-checking its work.

For the first time, the agency will also publish several operational metrics, including how the bureau counted a household (or an address, if vacant) — through self-response, in-person or proxy interview, or using administrative records, for example — and how those methods were distributed across geographic areas.

In another first, the bureau has let the American Statistical Association (ASA) conduct its own review of census operations. The ASA will release its own reports on the quality of the decennial census data throughout the year.

Q: Can states challenge their apportionment results?

A: Yes. In the modern era, states have challenged their loss of a House seat or failure to gain one in court, but without success. In 2001, the state of Utah sued the government, saying its refusal to count Mormon missionaries living abroad cost Utah the chance to add a House seat after the 2000 Census. The seat, which Utah missed gaining by just 857 people, went instead to North Carolina. The Supreme Court upheld the bureau’s actions, and similar challenges have been unsuccessful.

This year, concerns about the quality of the census may make it more likely for a state that fell just short of keeping or adding a seat to challenge the results.

Congress could also increase the number of House seats but is unlikely to do so anytime soon.

This FAQ will be updated.