Census Analysis Shows Undercount of Youngest Population in 2020

Based on new demographic analysis of 2020 Census population counts, the Census Bureau estimates that children between the ages of 0 to 4 were undercounted by over one million. This age range is historically undercounted in the population surveys but with the addition of conducting the decennial census in the midst of a pandemic, the cohort of the youngest children were undercounted at the highest level since 1970.

This undercount estimate is based on demographic analysis conducted by the Census, which uses birth/death records, international migration data, and Medicare enrollment data to produce separate population estimates from the decennial census survey. Birth records provide a better estimate for counting young children because these records are considered 100% complete providing full coverage of this young age group. The Census Bureau continues to research ways to improve survey estimates for this age group because of the consistent issues in the survey data.

By age group, the 0-4 age group was by far the most undercounted, at an estimated -5.4%. The age group 18-24 was the most overcounted at an estimated 3.5%. This age group was the only one less than 60 years of age that was overcounted.

Within the 0-4 age group by state, every state was estimated to be undercounted. The District of Columbia was undercounted by 15.6%, followed by Florida which was undercounted at 9.9%. Vermont was the least undercounted at 0.02%.

At the county level, demographic analysis was conducted for any county with an estimated population greater than 1,000 for children between 0-4. Of all U.S. counties, 84% were undercounted while the remaining 16% had no estimated error or were overcounted. The highest overcounted county was Meade County, South Dakota at an estimated 24.8%, while the most undercounted county was Fairfax City, Virginia at 25.2%.