2020 Census: Bureau Released Apportionment and Redistricting Data, but Needs to Finalize Plans for Future Data Products

What GAO Found

This report is the sixth in a series of updates on the Census Bureau's (Bureau) 2020 Census activities and operations. This update includes information related to census operations since our December 2020 report, such as the release of two key data products, plans for protecting the confidentiality of respondent data, and the status and progress of remaining operations for assessing the quality of the data.

Since GAO's last update in December 2020, the Bureau has completed data processing for two key data products. Apportionment population counts, which are used to distribute the 435 seats in the U.S. House of Representatives among the states, were released on April 26, 2021. Redistricting data, which include the local area counts states need to redraw legislative boundaries, were released on August 12, 2021.

The Bureau is required by law to protect respondent confidentiality. To that end, the Bureau implemented a new disclosure avoidance method in its 2020 Census redistricting data. However, the Bureau's schedule to protect respondent privacy in future data products does not provide specific dates for the disclosure avoidance activities the Bureau intends to complete. The success of a program depends in part on having a reliable schedule that defines when work will occur. Without a specific and complete schedule, the Bureau may be unable to accurately plan for and track progress on disclosure avoidance steps for future data products.

Remaining operations to assess census data quality include the independent post-enumeration survey (PES). The PES is conducted for a sample of the population to estimate how many people and housing units were missed or erroneously counted in the census (i.e., counted more than once, such as students who are counted at college and at their respective home addresses). The PES also produces undercounts and overcounts of the population by demographic characteristics.

However, the PES has experienced challenges due to the pandemic. For example, the Bureau stated that PES schedule delays may decrease respondents' ability to recall where they were living on Census Day because it occurred more than a year prior to the PES. Bureau officials have taken steps to mitigate risks such as adding the year 2020 for PES data collection as a point of reference. Bureau officials said they will be transparent about the survey data's limitations.

The Bureau reported that 2020 PES results will be released later than planned. National and state estimates of people undercounted or overcounted were expected in June 2021 and October 2021, respectively. However, Bureau officials released the national estimates of person coverage on March 10, 2022, and state estimates are expected to be released by June 30, 2022.

Why GAO Did This Study

In response to the COVID-19 national emergency, the Bureau made major and unprecedented adjustments to its plans for the 2020 Census. Operational delays led to the delayed release of the apportionment numbers and redistricting data products. The Bureau is evaluating the effect these adjustments had on the quality of the data collected.

In recent years, GAO has identified challenges to the Bureau's ability to conduct a cost-effective count, including new innovations and acquisition and development of IT systems. In 2017, these challenges led GAO to place the 2020 Census on its High-Risk List.

GAO was asked to provide regular updates on the 2020 Census. This report focuses on the Bureau's plans for protecting the privacy of respondent data, and its post-data collection activities to assess data quality. To describe the Bureau's plans for protecting the privacy of respondent data for the 2020 Census, and its post-data collection activities we reviewed documentation on the status and plans for disclosure avoidance activities and for selected operations relevant to assessing data quality.