Press Release | July 29, 2021 Statement on Differences Between 2020 Census and ACS 1-Year Estimates The data collection methods for the 2020 Census and the ACS are different[...]

July 29, 2021 - The data collection methods for the 2020 Census and the American Community Survey (ACS) are different. The 2020 Census is a count of all people living in the United States. In contrast, the ACS is a sample survey which relies on data from a relatively small number of people to represent the larger population. And because the processes for producing these data are different, so is the impact of the COVID-19 pandemic on the programs.

For the 2020 Census, the Census Bureau was able to overcome pandemic-related challenges by extending data collection and pouring additional resources into ensuring response. The 2020 Census deployed over 200,000 enumerators working throughout the nation, compared with roughly 2,200 field representatives who collected responses for the ACS. That was possible because the decennial census measures our population at a particular point in time: April 1, 2020. This proved effective for the 2020 Census. At the end of data collection, the 2020 Census was able to account for over 99.9% of addresses nationwide. The Census Bureau plans to release redistricting data - derived from the 2020 Census - by August 16, 2021.

For the ACS, a survey that collects data monthly and combines 12 months of data, extending data collection for additional months was not an option, so the survey was not able to adjust adequately to pandemic-related data collection challenges. As a result, the 2020 ACS data collection had the lowest response rate in the history of the survey at 71%. This is down from 86% in 2019, and 92% in 2018. The 2020 ACS 1-year estimates produced using the reduced-number of responses do not meet the Census Bureau's Statistical Data Quality Standards designed to ensure the utility, objectivity and integrity of the statistical information. Because of this, the Census Bureau will not release standard 1-year estimates from the 2020 ACS. Instead, the Census Bureau will release experimental estimates developed from 2020 ACS 1-year data. Additionally, we are still reviewing the quality of the 2016-2020 ACS 5-year estimates against our Statistical Quality Standards and tentatively plan to release them in December. More details will be announced this fall.

The Census Bureau is committed to providing high-quality data and transparency about efforts to ensure that the 2020 Census and survey counts are the highest quality possible and fit for their many uses.

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