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Resources Available to Prepare for the 2020 Census Redistricting Data Release

July 28, 2021
By James Whitehorne, chief, Redistricting Data and Voting Rights Office

Estimated reading time: 4 minutes

In a few weeks, we’ll release the 2020 Census redistricting data in our legacy summary file format. And a few weeks after that, we’ll release the same data in an easier-to-use format.

We’re releasing the same data twice but in different formats at different times to make sure states get the data as quickly as possible. Acting Director Dr. Ron Jarmin explained these two releases in his blog, Redistricting Data: What to Expect and When. In this blog, I provide more detail about the formats and support materials available, particularly for the first release.

First Data Release by August 16

By August 16, we will provide redistricting data on our public FTP site in the summary file format we’ve provided in past decades.

The format consists of a group of pipe-delimited text files that include:

  • A geographic header (geoheader) file that contains the geographic information.
  • Three separate data segments per state that contain the data tables. Because of the number of fields, we've separated the data tables into three data segments:
    • Data segment 01 contains tables P1 – Race and P2 – Hispanic or Latino, and Not Hispanic or Latino by Race.
    • Data segment 02 contains tables P3 – Race for the Population 18 Years and Over, P4 – Hispanic or Latino, and Not Hispanic or Latino by Race for the Population 18 Years and Over, and H1 – Occupancy Status.
    • Data segment 03 contains table P5 – Group Quarters Population by Major Group Quarters Type.

This format requires data users to use additional software and perform extra work to extract the data. To help states and other data users prepare, we’ve provided a number of materials. All of these materials are available on our Redistricting Data Program Management page. The materials include:

  • Prototype data. These data come from the 2018 End-to-End Census Test in Providence County, R.I., and are in the same format that will be available from the 2020 Census. We produced a prototype product to illustrate what states can expect. This prototype is used to build and test systems in advance of the official data release so that states can begin work immediately when they receive the 2020 data.
  • Microsoft Access database shell. The shell comes with a step-by-step guide on how to use it to import the redistricting data and extract data from the files. The shell serves as a template for extract queries by blocks, counties and county subdivisions.
  • A list of frequently used geographic summary level codes. All data are available at coded levels specific to the type of geography, including states, counties, places, congressional or legislative districts, voting districts, census tracts, and blocks. Users can check this list to look up the summary level code that corresponds to some of the most commonly used types of geography.
  • SAS import scripts. These scripts help users import the data files into the SAS statistical software.
  • R import scripts. These scripts help users import the data files into the R statistical software.
  • Geographic support products. These products will help users map the actual 2020 Census data and redraw district boundaries. The products include shapefiles for the new 2020 Census blocks and updated boundaries for legal governments referenced to January 1, 2020, as well as other geographic information.

We’ve also created a video to show how to download, import and extract the data from the summary files.

Second Data Release by September 30

We are focusing on getting the first data release out as quickly as possible and aim to include data visualizations and analysis either with that release or as soon as possible after it. 

We’re also working to provide easier-to-use formats by September 30. In response to feedback we received after the 2010 Census, we decided when planning the 2020 Census that we would release the redistricting data in more user-friendly formats to empower everyone to access and use redistricting data.

By September 30, we will provide the same redistricting data we provided in August but in two additional formats that are easier to use:

  • We will provide a toolkit in the form of DVDs and flash drives to the state officers (or their designees) and to any other public bodies responsible for their state’s legislative apportionment or districting.
    • The DVDs and flash drives will contain an integrated software browsing tool. This tool allows for intuitive browsing of the data.
    • The DVDs and flash drives will also include an extraction menu that allows for the easy extraction of large datasets. These datasets can then be imported into a Geographic Information System (GIS) or database.
  • The states and the public will be able to access the data through the Census Bureau’s primary data dissemination tool, the data.census.gov platform.

We originally planned to provide the toolkits and data.census.gov platform as our primary methods of delivering the redistricting data, while simultaneously releasing the legacy format summary files on our FTP site. However, COVID-19-related delays and other processing decisions altered our schedule.

Adding the earlier release of the summary files (and providing tools to help data users prepare) was the best way to get the data to all the states as soon as possible.

We want to assure states that we are confident in their quality of this data for legislative redistricting, we would not release them otherwise.

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