(CNN)Latino, Black and Native American populations were significantly undercounted in the 2020 census, officials announced Thursday.
The undercount rate for the Latino population was more than three times the rate for that group in 2010, according to Census estimates.
Overall, officials estimate .24% of the nation's population, or about 782,000 people, were missed in the count. That margin wasn't statistically significant, officials said, but the undercount rates for certain demographic groups were.
The census, which occurs every 10 years, is the basis for determining how many representatives each state gets in Congress and how an estimated 1.5 trillion dollars in federal funding are spent.
Even before the 2020 count had ended, demographics experts, local officials and advocacy groups were sounding the alarm, warning that the pandemic and politics were getting in the way of an accurate count.
Census Bureau Director Robert Santos acknowledged those concerns Thursday while announcing the undercount analysis, which he said was based on two independent studies to measure the quality of the 2020 count.
"The Census Bureau faced an unprecedented set of challenges over the last two years. Many of you, myself included, have voiced concerns. How could anyone not be concerned?" Santos said in recorded remarks. "Today's findings will put some of those concerns to rest and leave others for further exploration."
For some groups, undercount rates went up
According to one estimate, known as the Post-Enumeration Survey, 18.8 million people were not counted correctly in the 2020 census. But about 10.9 million people in that group were ultimately counted in a statistical process known as imputation, which is used for addresses that did not respond. More than 7 million others were erroneously counted, largely due to duplication. In the end, officials said the bureau's count of the total US population was accurate.
The Latino population undercount rate in the 2020 census was 4.99%, more than three times the rate for that group in 2010, according to the Census. The undercount rate of people who identify as "some other race" also increased significantly, from 1.63% in 2010 to 4.34% in 2020.
Officials said undercount rates of other groups were significant, but statistically similar to past results. The Black population's undercount rate was 3.3%, while the undercount rate for American Indian and Alaska Native populations living on reservations was 5.64%.
Other groups were overcounted in the 2020 census, according to the estimates. The non-Hispanic White population's overcount rate was 1.64%, while the Asian population's overcount rate was 2.62%.
One advocate calls the results 'completely unacceptable'
Word of the Latino population undercount drew sharp criticism from Arturo Vargas, CEO of the National Association of Latino Elected and Appointed Officials Educational Fund, who described the 2020 census as a "five-alarm fire."
"A 2020 Census that more than tripled the percentage of undercounted Latinos from Census 2010 is completely unacceptable and further demonstrates the dire need for our nation to make fundamental changes in how we count U.S. residents," Vargas said in a statement.
Santos said the quality of the total population count is "robust and consistent with that of recent censuses," something he described as "notable" given the challenges the 2020 count faced.
"Taking today's findings as a whole, we believe the 2020 Census data are fit for many uses in decision making, as well as for painting a vivid portrait of our nation's people. Yes, there are areas of concern, and we'll be exploring those further," Santos said.