The August 12, 2021 Release of 2020 Census Redistricting Data, Explained

By Sonni Waknin, Tye Rush and Katarina Rusinas

On August 12, the U.S. Census Bureau will kick off the 2021 redistricting cycle by releasing its local level results from the 2020 Census. The method for releasing this data this year is different from past years. Notably, the Census Bureau is releasing what it calls the “legacy format” data. The data will provide every jurisdiction in the country with information on its voting age population, including information about race and Hispanic origin, based on the 2020 Census. Jurisdictions will use this data to redraw the district maps used to elect Congressional, state, and local officials so that they reflect population change. (For more information on redistricting, follow this link).

What is the Decennial Census?

Article I, Section 2 of the U.S. Constitution requires a counting of every U.S. resident every 10 years. The Census Bureau was created and tasked to carry this out in the form of the Decennial Census, which occurs at the start of every decade (2020, 2010, 2000, etc.). The 2020 Decennial Census took place during the COVID-19 pandemic and was marred with issues.

If the census is in 2020, when does redistricting occur?

Normally, if states have requested the redistricting data, the Census Bureau is required to deliver it by April 1 of the year following the Census, so years ending in ‘1. States then spend until October of the following year –years ending in ‘2– redistricting. Then, by November of that same year (ex: 2022), candidates for the House of Representative run for the seat in the redrawn district. The elected candidate is inaugurated the following January.

Why is this year different?

Typically, Redistricting Data, called the PL 94–171 data, includes tabulations on key statistics like total population, summaries for the major racial groups, Hispanic origin, and voting age. Due to obstacles in the 2020 Census, the Census Bureau has been significantly delayed in releasing the data. This is a problem because the delay would encroach on states’ deadlines to redistrict, creating conflicts with certain states’ obligations under their respective state constitutions.

To address this issue, the Census Bureau announced on March 15, 2021 that it would provide states with an initial release of the 2020 Census data in “legacy format” by August . The standard, PL 94–171 redistricting data is set to be released more than a month later by Sept. 30.

What is legacy format data?

While the legacy format data is subject to the same quality control as the data states will receive in the PL 94–171 Redistricting Data file, the legacy data will be packaged in an older format that is less user friendly. The legacy format, which was used in the 2010 and 2000 Redistricting Data files, requires states themselves to tabulate the data. In order for states and jurisdictions to use the legacy format data for redistricting, states will have to either create or buy software that will import the data, establish relationships between the data files, and correctly pull the subset of records in certain fields to match to the proper geography and data categories being requested. The forthcoming September 2021, 2020 PL 94–171 Redistricting Data will be in a different and simpler system for accessing the data that ensures the redistricting data is correctly matched to the proper geography.

The reason that the legacy data is important in this redistricting cycle is because states that need to be relieved of their deadline pressures for redistricting will use the legacy data by packaging the legacy data to data kits they have used previously. What is at issue is that while the legacy data will be delivered to states sooner, some states may not have the capacity to process it, creating the potential for incorrect data to be used in the redistricting process. This problem can be alleviated, however, if states and jurisdictions work with experienced experts in census data to correctly pull the proper geographical and data files together.

¹ Congressional Research Service, Apportionment and Redistricting Process for the U.S. House of Representatives (May 12, 2021), https://crsreports.congress.gov/product/pdf/R/R45951#_Toc21686917.

² Press Release, U.S. Census Bureau, Statement on Release of Legacy Format Summary Redistricting Data File (Mar. 15, 2021), https://www.census.gov/newsroom/press-releases/2021/statement-legacy-format-redistricting.html.