Why it's hard to know how accurate the 2020 census was

No census in the U.S. has been perfect.

Exactly how imperfect the national head count was in 2020 may start to be revealed in a report the Census Bureau is set to release Thursday.

While the 2020 census may now seem like a distant memory, any confirmed over or undercounts carry both near and long-term implications on how political representation and federal money are distributed in the United States.

Disruptions from the coronavirus pandemic, historic hurricane and wildfire seasons and years of interference by former President Donald Trump's administration made it especially difficult for the bureau to try to count every person living in the country. These extraordinary challenges have also made it harder to pinpoint the tally's accuracy.

For the next decade, any census errors would be baked into the data used to reallocate each state's share of congressional seats and Electoral College votes; redraw voting districts for every level of government; help distribute an estimated $1.5 trillion a year in federal funds for public services; and form the country's understanding of who lives in the United States.

Here's what else you need to know to decode the Census Bureau's upcoming data quality report:

The over or undercount of the total population masks racial inequities

After the 2010 count, the bureau's director at the time, Robert Groves, called the tally "an outstanding census" for having a net overcount of the total U.S. population of 0.01%, which translates into overcounting by about 36,000 people.

Focusing on just that sliver of a percent, however, would mean overlooking a stark flaw along racial and ethnic lines: Decade after decade, the U.S. census has overcounted people who identify as white and not Latino, while undercounting people of color. The 2010 tally was no exception.

Civil rights organizations and other census watchers are concerned this trend is likely to have continued in 2020, perpetuating inequitable distributions of political power and federal money for another 10 years.

COVID-19 made it harder to measure who was left out of the count

Just as the pandemic disrupted door knocking for the census, it also delayed in-person interviews for the follow-up survey the bureau relies on to determine over and undercounting rates by race, ethnicity and other demographic characteristics.

That has many census watchers worried about how accurate the results of the Post-Enumeration Survey will be.

Faced with many households' reluctance to speak with strangers at their doors and general census fatigue, the bureau extended the survey's interviewing schedule. The shifts raised the risk of households not accurately recalling who was living at their home address on Census Day, which was April 1, 2020.

Still, bureau officials have said that despite the challenges, they believe the survey's estimates "will produce a helpful picture."

Quality metrics at the state level and lower would tell a fuller story

The bureau says Thursday's report – the first of a series on the quality of the 2020 census data based on Post-Enumeration Survey estimates – will provide only a national-level look.

Counting efforts can range greatly from neighborhood to neighborhood, which means to get a fuller story on the accuracy of the 2020 tally, metrics at the state level and lower are needed.

Estimates by state are expected from the bureau this summer. However, the survey is not conducted in remote areas of Alaska. It also does not include people experiencing homelessness or those living in college dorms, prisons or other group quarters, where residents were particularly difficult to count accurately in the early months of the pandemic.

In December, the bureau announced it is not planning to release new over and undercounting rates for counties and smaller local communities and needs to do more research on how to produce those quality metrics below the state level.

Copyright 2022 NPR. To see more, visit https://www.npr.org.

• Trump is named Time's Person of the Year, will ring the New York Stock Exchange bell
• Ontario premier says U.S. energy exports will be cut off if Trump imposes sweeping tariffs on Canada
• FBI Director Wray to resign at end of Biden administration
• Kimberly Guilfoyle is the latest Trump family ally chosen for an ambassadorship