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SALT LAKE CITY — More than 1 million children between the ages of 0 and 4 may have been undercounted during the 2020 census, marking the largest undercount of any age group in the nation, according to the U.S. Census Bureau.
However, "new experimental estimates" the agency released on Thursday show Utah had the third-lowest rate of undercounts in the nation, and a few Utah counties even bucked a trend that swept through most of the country.
"Our goal is to accurately count every child in the census and to ensure they are fully represented in our surveys," said Census Bureau director Robert Santos in a statement. "Quality statistics help communities better understand their needs and seek resources."
Federal demographers now estimate there were nearly 19.5 million children between the ages of 0 and 4 at the time of the 2020 census, which was a count of everybody living in the U.S. as of April 1, 2020. They used birth and death records from the National Center for Health Statistics, international migration data and Medicare records to create a "demographic analysis estimate."
The new estimate is about 1.06 million above what residents reported to the agency during the decennial count four years ago, meaning the census may have been off in this category by about 5.46%.
The rate was higher in some areas. For instance, the demographic analysis estimate indicates that young children in the District of Columbia were undercounted by nearly 16%, while Florida had the highest undercount among states at nearly 10%. Hawaii, California and Texas rounded out the top five in undercounts among the U.S, with census counts ranging from 7.7% to 9.7% below new estimates.
While every state ended up with an undercount in this age bracket, Utah had one of the lowest rates. The Census Bureau estimates there were 241,052 children between 0 and 4 living in Utah on April 1, 2020, almost 1,300 more than what was listed in the census, off by about 0.53%. Only Idaho (0.44%) and Vermont (0.02%) had estimates closer to the 2020 census.
But seven Utah counties wound up with population overcounts of children between 0 and 4. Box Elder (1.6%), Cache (2.54%), Davis (0.37%), Summit (2.01%), Uintah (0.52%), Utah (1.65%) and Wasatch (4.22%) counties all had estimates lower than the 2020 census, while every other county either had an undercount, or there was enough data to complete an analysis.
Duchesne County — with a difference of about 171 — had the highest undercount percentage in Utah. Its census percentage was about 10% below the new demographic analysis estimate.
In all, slightly fewer than 300 U.S. counties had overcounts among the over 1,900 counties with enough data to be included in the analysis. Meade County, South Dakota, had the highest overcount in the nation, as its census count was about 25% over the new estimate, besting — ironically — Meade County, Kentucky, which was second at 15%.
It's not quite clear why so many children were undercounted in 2020. Santos said the agency is aware undercounts are "often correlated with undercounts of certain race and ethnicity groups along with other factors" that the agency is "not able to measure directly."
Agency officials explained that net coverage errors varied because of different factors, such as geography, race and Hispanic origin, household structure and "other demographic, social and economic characteristics."
Eric Jensen, a senior adviser for population estimates and coverage measurement for the agency, said some undercounts might be "inflated." The District of Columbia, for example, could be higher because mothers living in Maryland or Virginia could have gone to a hospital in the district.
He also noted counties with overcounts tended to be "less spread out." He pointed to Utah as an example of a state that had "some clustering" among counties with overcounts.
The finding comes close to two years after the Census Bureau revealed that Utah — the fastest-growing state in the nation between 2010 and 2020 — had one of the highest overall population overcounts in the U.S. Experts said, at the time, overcounts typically happen when people accidentally fill out forms twice for two residences or separated parents with split custody each fill out a child living at their residence.
The findings don't change the results of the 2020 census — a tool used to inform federal leaders on how to allocate funds and representation across the nation — but offer a better window into U.S. demographics. It can also help the agency improve data collection for the next census six years from now.
"They offer a unique glimpse into the geographic distribution of the coverage of young children in the 2020 census and are critical in identifying areas where improvements are needed to more accurately count children in the 2030 census," Jensen said.
