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For Immediate Release: Thursday, May 19, 2022

U.S. Census Bureau Releases 2020 Undercount and Overcount Rates by State and the District of Columbia

Press Release Number CB22-CN.08

Coverage Rates by Census Operation for the Nation Also Now Available

MAY 19, 2022 — The U.S. Census Bureau today released the 2020 Census estimated undercount and overcount rates by state and the District of Columbia from the Post-Enumeration Survey (PES). Also released today are estimated coverage rates by census operation. This includes coverage rates by mode of self-response, and by respondent type in the Nonresponse Followup operation.

“The release of these PES estimates assists us in understanding how well we did this decade, state by state, in our efforts to count everyone living in the United States,” Census Bureau Director Robert L. Santos said. “Transparency is a critical aspect of scientific integrity. That is why we are releasing these results to the public. Our assessments – including the 2020 Census  quality indicators, the PES, and the Demographic Analysis released earlier this year – offer valuable insights into the quality of the 2020 Census counts. Although none of the assessments alone can be considered definitive since no “true count” of the population exists, today’s PES results suggest that some states experienced undercounts or overcounts.”

The PES estimates show how well the 2020 Census counted everyone in the nation by creating an independent estimate of the number of people living in the United States on April 1, 2020 (excluding people in group quarters, such as nursing homes or college dorms, and people in Remote Alaska areas), surveying a sample of people in households in the United States and matching those responses to their records in the 2020 Census.  

“Achieving an accurate count for all 50 states and DC is always a difficult endeavor, and these results suggest it was difficult again in 2020, particularly given the unprecedented challenges we faced,” Santos added. “It is important to remember that the quality of the 2020 Census total population count is robust and consistent with that of recent censuses. However, we know there is still more work to do in planning future censuses to ensure equitable coverage across the United States and we are working to overcome any and all obstacles to achieve that goal.”

This release includes:

  • Undercount and overcount estimates for states, the District of Columbia (a state equivalent) and regions.
  • Components of coverage by state and the District of Columbia to estimate the proportions of census records that are correct, wrong, or we don’t have enough information to be sure one way or the other. They include correct enumerations, erroneous enumerations, whole-person imputations, and omissions.
  • National components of census coverage: Correct or erroneous enumerations and whole-person imputations by census operation and mode, including self-response by mode (internet, telephone, paper) and Nonresponse Followup by type of enumeration.

Key findings:

  • 37 states (or state equivalent) did not have estimated statistically significant undercounts or overcounts.
  • 14 states (or state equivalent) are estimated to have had an undercount or overcount – a net coverage error statistically different from zero – meaning they were either undercounted or overcounted.
    • Undercount: Arkansas (-5.04%), Florida (-3.48%), Illinois (-1.97%), Mississippi (-4.11%), Tennessee (-4.78%) and Texas (-1.92%).
    • Overcount: Delaware (+5.45%), Hawaii (+6.79%), Massachusetts (+2.24%), Minnesota (+3.84%), New York (+3.44%), Ohio (+1.49%), Rhode Island (+5.05%) and Utah (+2.59%).
    • Visit the data visualization for a look at coverage for all states and the District of Columbia.
    • See Appendix Table 3 on page 16 of the PES report for PES estimates in 2010 and 2020 as a reference. However, it is important to note that we have improved the methods we use to estimate 2020 state-level net coverage errors and their margins of error. These improvements were designed to reduce the bias of the state coverage estimates and more accurately measure the sampling error of the estimates. That means any such comparison of estimates is subject to two different sources of error and uncertainty, and while informative, the comparison cannot be considered definitive. We discuss the 2020 PES methodology in more detail in the Source and Accuracy Statement
  • See the Post-Enumeration Survey Estimation Report for the complete list of 2020 PES estimates, as well as respective measures of uncertainty in the PES estimates. For each estimate, we provide a measure of sampling error that reflects the range of possible values because the estimate is based on a survey sample.
  • There was an estimated undercount in the South region (-1.85%) and an estimated overcount in the Northeast region (+1.71%).

“These results give us valuable insight as we plan operations and allocate resources for the 2030 Census,” Santos said.

The PES results are necessarily limited due to the limited size of the samples. Results cannot reliably be broken down by demographic characteristics or geographic areas within states. Note that for the 2010 PES, the Census Bureau also was unable to release state estimates of coverage by demographic groups within states. Given 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.

“I continue to be proud of the efforts of our career staff and appreciative of our community partners,” Santos added. “Their collective talent, tenacity, and dedication to our mission enabled us to achieve a much better count than many thought was possible.”

The Census Bureau released the first results from the PES along with additional results from the 2020 Demographic Analysis (DA) on March 10. The 2020 Census Quality indicators were released starting on April 26, 2021. Together, these products represent important contributions to understanding the quality of the 2020 Census and planning for the 2030 Census. The first release of PES results provided national estimates of population coverage overall and by demographic groups, such as race and Hispanic origin, as well as age groups and sex. DA results included national net coverage error estimates by age and sex. And the 2020 Census quality indicators shed light on the quality of the 2020 Census operations, themselves.

In addition to releasing the report on Census Coverage Estimates for People in the United States by State and Census Operations, the Census Bureau also released a technical report describing methods and results on imputing demographic characteristics for the PES. A technical report describing methods and results used to reduce nonresponse errors in the PES for person estimates is also available.

The remainder of the PES estimates, including results for housing units, and undercount and overcount rates for Puerto Rico, are scheduled for release in the summer.



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301-763-3030 or
877-861-2010 (U.S. and Canada only)


Page Last Revised - June 1, 2022
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