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RESEARCH BRIEF  |  Children  |  November 2023


In partnership with Dr. Bill O’Hare, Count All Kids, this research brief estimates the 2020 Census undercount of Texas young children by county and studies county-level and regional patterns across the state to enable thorough analysis and informed decision-making.

By: Dr. Francisco A. Castellanos-Sosa, Texas Census Institute, Senior Research Associate
Dr. William P. O’Hare, Count All Kids Campaign, Consultant


The Children’s Census Initiative

The Texas Census Institute created the Children’s Census Initiative to improve the accuracy with which the 2030 Census will count Texas children. The initiative comprises five related parts, each tackling a specific aspect of this phenomenon to enable a thorough analysis and informed decision-making. This research brief is the third product of the initiative. Its objective is to demonstrate the undercount of young children, age 0-4, by county in Texas. In addition to the already published research on the child undercount in Texas (age 0-17) by county and counties with a high child undercount, upcoming research in this initiative includes a look at the funding implications of the child undercount due to a loss of federal dollars, and the potential determinants of the undercount. Collectively, this initiative will offer valuable insights and recommendations for addressing the U.S. Census child undercount and empowering stakeholders with the knowledge for effective decision-making and action.

Research Overview

Estimates suggest the 2020 Census undercounted 155,855 Texas young children in net terms (7.9% of Texas children). While these state-level numbers are informative, some counties experienced much higher undercount rates. To better understand this issue, we examine the 2020 county-level high net young child undercount in Texas and study its spatial distribution using data from the 2020 Census and the Vintage 2020 Population Estimates. This study builds on the work of Dr. William P. O’Hare, who finds Texas had more counties with high net undercounts of young children than any other state (either in number or rate terms).

Main Findings

Of the 1,975,115 children in Texas reflected in the Vintage 2020 Population Estimates, the 2020 Census undercounted 155,855 young children (7.9%).
184 of 254 Texas counties (72.4%) had a high net young child undercount (rate, number, or both).
85.8% of Texas young children live in a county with a high undercount (rate, number, or both).
Of the 184 Texas counties with a high net young child undercount, 31 Texas counties had a high net young child undercount rate and number, with a net 134,421 young child undercount (9.5% of their children).
12 of the 14 Texas counties on the U.S.-Mexico border have high net young child undercounts (rate, number, or both).
Altogether, the 14 counties on the U.S.-Mexico border have a net young child undercount of 31,666 (15.2% of their young children).

Figure 1 Net undercount rate for children’s age groups: 1970-2020.

Source: Jensen, E. B. Census Bureau Expands Focus on Improving Data for Young Children. United States Census Bureau. U.S. Census Bureau. America Counts Series (2022).
Note: Negative and positive values indicate net undercounting and net overcounting, respectively.

Concluding Remarks

The data examined here indicate that the undercount rate for the population aged 0 to 5 in the 2020 Census (also known as young children) is a substantial issue across a large number of Texas counties. Altogether, there are 184 counties in Texas with either a high net young child undercount rate or number. Strikingly, about 85.8% of all young children in Texas live in a county of this type.

There were 180 counties with a rate above 5.0%, 35 counties with a number above 500, and 31 counties with a high net young child undercount rate and number.

The findings provided in this brief aim to contribute to our understanding of the quality of the 2020 Census at a more granular level since state-level measures often mask large differences among counties. Absent more updated information, the information in this study can be used to start targeting outreach and promotion to improve the count of young children in the 2030 Census.

This information about where the undercounts of young children are the highest in Texas could help the U.S. Census Bureau and census stakeholders prepare for the 2030 Decennial Census. The data presented in this study are useful to pinpoint the types of places that deserve special attention in the 2030 Census concerning the count of young children. This report may serve as a model for other states to understand their net young child undercounts.

Finally, researchers could also use these findings as a starting point to examine the characteristics that distinguish counties with high net young child undercounts from other counties. Identifying those characteristics may help us reduce net young child undercounts in the 2030 Decennial Census by addressing its root causes.

Author’s Message

The net undercount of young children (age 0 to 4) in the U.S. Census is high and has been growing in recent decades. This study provides a detailed analysis of high young child undercounts at the county level in Texas and explores its regional patterns. These results can serve as a roadmap for deeper analysis.

Census-related data are used to determine the distribution of funding for 350+ federal programs, totaling more than $2.8 trillion each year. Counties with an undercount will not receive the full federal funding to which they are entitled, impacting budgets for things like schools, health centers, and childcare centers. Furthermore, counties with an undercount will not have accurate data for future planning.

To address the impact of an undercount, leaders may want to explore ways to compensate counties that experience a high undercount of children. Similarly, leaders in counties with a high undercount of young children may want to work with the Census Bureau to look for additional ways to correct the undercount of young children in future censuses. The results shown here can be used to start building a targeted approach to increasing the count accuracy of young children in the 2030 Census.

Acknowledgements: The authors appreciate the insightful support provided by Helen You, Deborah Stein, and Monica Cruz.


1) Why does the U.S. Census Bureau not publish undercounting and overcounting estimates at the county level for children?

As it is well known, the U.S. Census Bureau assesses the quality (undercounting or overcounting) of its Decennial Census using the Post-Enumeration Survey (PES) and the Demographic Analysis (DA). 

The PES was implemented in 2020 by characteristics of the housing units only to the national and state levels. The PES uses the location of the housing units to obtain results at the subnational level, but it does not consider demographic characteristics such as age or gender. Moreover, “…the sample size for the 2020 PES and the assumptions required to make unbiased sub-state estimates, the Census Bureau was unable to include county or place estimates in the 2020 PES reports, as well.” (U.S. Census Bureau, 2022). 

On the other hand, the Demographic Analysis uses “…current and historical vital records, data on international migration, and Medicare records to produce national estimates of the population on April 1 by age, sex, the DA race categories, and Hispanic origin.” (U.S. Census Bureau, 2022). While the DA is rich in demographic characteristics, it cannot identify the current place of residence of the population since a great part of it is based on vital records. Therefore, due to its nature, the official undercounting or overcounting by demographic characteristics is estimated at the national level only.

Therefore, it is not possible to obtain an official undercounting and overcounting estimate at the county level for children.

2) Why are we using counties as geographies?

This approach implies that undercounting estimation is built upon variables that are considered determinants of undercounting, according to the theory.

3) How accurate or precise are our net child undercount estimates?

While there is no statistical measure of accuracy or precision for our estimates, they were built using official publicly available data from the U.S. Census Bureau.

4) Why are we focusing on counties with high net child undercounts?

Given the potential small random errors in the 2020 Census and the Vintage 2020 Population Estimates, a small difference between them might not necessarily reflect a true net undercount or an overcount. While small net undercounting can be important, our contribution relies on identifying the Texas counties where the net child undercount could be considered a serious problem. By focusing only on counties with high net child undercounts, we are more likely to identify the correct direction of net child undercount.