County-level Coverage Rates of Young Children in the 2020 Census: The National-Level Data Do Not Tell the Full Story

This study extends a set of analyses that address one of the biggest problems in terms of the accuracy in the U.S. Decennial Census, namely the high net undercount of young children.

The data examined here indicate that the net undercount rate for the population age 0 to 4 varies substantially across counties. Nearly 70 percent of all counties had a net undercount of the population age 0 to 4.

Data examined here also show there is a great deal of variation in net young child undercount rates across the country. Consequently, the national rate does not reflect the experiences in most counties. This underscores the importance of developing subnational rates.

Analysis here addresses the geographic distribution of the net undercount of young children in the 2020 Census among counties. Analysis shows counties in the South and Southwest have much higher net undercount rates than counties in the Northeast and Midwest. Of the ten states with the highest percentages of counties with young child net undercounts of 5 percent or more, nine are in the South and Southwest.

Moreover, the data show that larger counties account for the vast majority of the national net undercount for the population age 0 to 4. In the 142 largest counties based on total population, there was a net undercount of 655,661 persons age 0 to 4 which accounts for about two-thirds of the nationwide net undercount for this age group.
The analysis indicates that the net undercount of young children is concentrated in the largest counties in the country. The concentration of the net undercount of young children in a relatively small number of large counties is a product of the large number of young children who live in those large counties and the relatively high net undercount rate for young children in those counties.

This information about where the net undercount rates for young children are the highest should help the U.S. Census Bureau and census stakeholders prepare for the 2030 Decennial Census. The data presented in this study will help the Census Bureau pinpoint the places that deserve special attention in the 2030 Census. However, it is important to recognize knowing where to focus attention is not the same as knowing what to do to improve the count of young children in the 2030 Census. There is still a lot of work to be done to develop plans that will reduce the undercount of young children in the 2030 Census.