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About Our Data

Learn more about the data hosted on the Redistricting Data Hub

Types of Data

Select each data type to read an in-depth description.

Precinct Boundary and Election Results
Precinct level election results merged with precinct boundaries are collected by our data partners. We peer review these files as part of our Partner Data Validation effort, and provide detailed reports for each validated dataset.
Voter Files
2021 Voter File data aggregated to 2010 census blocks are available for all states. This data was purchased by the Redistricting Data Hub from L2, a national voter file vendor. All states now reflect voter file data updated after 2020 general election data.
Incumbent Addresses
The incumbent address data gathered by Dr. Carl Klarner provides information about current incumbents, including their district number, party registration, gender, race and address. Users will need to request permission to download this data.
Population Projections
HaystaqDNA produced 2020 – 2030 population projections aggregated to the 2010 and 2020 census block and block group levels split into P1 and P2 fields of the PL redistricting file. They are available in CSV and SHP formats.
PL 94-171
The PL 94-171 dataset is the Redistricting Data File created by the U.S. Census Bureau for use by the states in redistricting based on the decennial census. In addition to tabulating the data, our team merged the census data with geographic information, so that it is ready to use in standard mapping softwares.
There are states that have a requirement for modifying the PL 94-171 data prior to redistricting, we maintain a references to those states’ constitutions, statutes, or other rules governing redistricting.
We have formatted a list of the fields and descriptions found in the PL 94-171 dataset found in the 2020 Census State Redistricting Data (Public Law 94-171) Summary File Technical Documentation
Legislative Boundaries
Legislative boundary files for 2011 to the present are re-hosted from All About Redistricting for each state.
American Community Survey (ACS)
Select fields from the American Community Survey 5-year estimates are available for 2010 to 2019 at the block group, census tract, county, and state level geographies in SHP and CSV format where applicable. The ACS collects a wide range of data, and on our site we host population totals by race and estimates for language spoken at home (not available at the block group level). For more information on field names, see the metadata of your desired dataset.
Citizen Voting Age Population (CVAP)
CVAP Special Tabulation data available for 2010-2019 at the block, block group, census tract, county, and state level in both SHP and CSV format. Additional CVAP data is available at the Place, SLDU, SLDL, MCD, and Congressional Districts level for 2018 and 2019. Fields were modified to match OMB race categories as used in voting rights analysis. The CVAP data contains estimates by race (for Non-Hispanic/Latino) for total population (not available at the block group or tract levels), voting age population (not available at the block group or tract levels), citizen voting age population, and citizen population. For more information on field names, see the metadata of your desired dataset.
TIGER Boundary Files
Boundary shapefiles are available at several geographies within a state, including blocks, block groups, census tracts, counties, or the entire state. For some states, this may also include 2020 Zip Code Tabulated Areas ZCTAs, American Indian, Alaska Native and Native Hawaiian AIANNH boundaries boundaries and Voting Tabulation Districts VTDs.
Community of Interest (COI) maps
We are currently collecting all community of interest maps submitted to legislative and congressional redistricting bodies and organizations during the 2021 redistricting cycle. We have already collected over 10,000 maps in 38 states, and have begun cataloging and uploading them to the Harvard dataverse.
Written public redistricting testimony
To complement the collection of community of interest maps, we have begun collecting any written or verbal testimony submitted to legislative or congressional redistricting bodies. This includes comments submitted through a portal or email, comments made during meetings, and comments attached to proposed maps
Official adjusted state redistricting datasets
Several states adjust the census data for congressional and/or legislative redistricting purposes, typically to reallocate incarcerated individuals to their last known address. We obtained and rehosted official adjusted datasets in all states but Rhode Island. We have also produced reports that outline the differences between unadjusted and adjusted data at various levels of geography.
Official adopted legislative boundaries
We are collecting and rehosting passed and enacted legislative and congressional plans as they become available.

Are you an expert witness, special master, or using our data in litigation?

Make sure you know these key points about our data

Learn More

Articles

How data is used in redistricting

Partner Data Validation

Learn more about how we ensure that the Precinct Boundaries and Election Results files that we host is accurate and reproducible

Census Data

Learn more about the decennial census and how to use this data in redistricting

Our Process

Partner Validation

The Partner Data Validation project is an ongoing effort by our Data Analysts to peer-review the files we re-host from our Data Partners, who have taken on the task of collecting and making Precinct Boundaries joined with Election Results publicly available for redistricting. In looking at the data being collected, the RDH has identified six criteria which we believe encompass most issues that may arise with these data. For each state and data partner, the report that we are writing describes in detail what we found for each of these criteria.

We do this because data is critical to court cases. Finding an error that could discredit the dataset can be debilitating and lead to the failure of an argument or defense in court. Additionally, the reports created highlight the benefits and draw-backs of a given partner dataset.

GitHub

We use Python and the SciPy ecosystem (NumPy, Pandas, GeoPandas, MatPlotLib) to carry out the majority of our validation work. At a high level, our process begins by locating Election Results and Precinct Boundaries datasets, cleaning and merging Election Results to Precinct Boundaries, and then comparing the resulting Precinct Boundaries and Election Results file to the equivalent files produced by our Data Partners.

Our API script is available on our GitHub, in order for the script to retrieve data you must be a designated API user. Request access to our API

For more information about our processes and to view our source code, visit our GitHub

Do you need data that isn’t already hosted by the data hub?

If you need a redistricting dataset we don’t have, let us know what you need and why

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How to Use our Data

Data in the Redistricting Process

Read our Redistricting Readiness Checklist to learn how to use this data in the redistricting process

Redistricting Process

Visit All About Redistricting to learn more about the rules, criteria, and litigation in each state. The website has information about the redistricting process in each state, including the timing, whether and how public input is incorporated, and criteria. The website is a great resource to consult before using our data to draw maps!

Draw or Analyze a Map

Use our Choose Your Own Mapping Tool to find the right software to draw a Community of Interest or District Map

Metadata

All of the information you need about a given dataset will be included in the metadata, including column/variable names, methods and processing decisions, sources, dates when the data was retrieved, and any other valuable information about the file. If you have a specific question, please reach out to us!

Access Our Data

There are two ways to access data: create a free account and download individual datasets or register as an API user and download multiple datasets at once

Register

Sign up for a free account to download data

Download data for your state

Browse the data available for each state and download datasets individually

API

Request access to use our Application Programming Interface (API) to download multiple datasets at once

Ask us a question

Our help desk team can answer your questions about our data and the redistricting process. Send them a message and they will respond within one business day!

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