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Decennial Census P.L. 94-171 Redistricting Data

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P.L. 94-171 Redistricting Data

Public Law (P.L.) 94-171, enacted by Congress in December 1975, requires the Census Bureau to provide states the opportunity to identify the small area geography for which they need data in order to conduct legislative redistricting. The law also requires the U.S. Census Bureau to furnish tabulations of population to each state, including for those small areas the states have identified, within one year of Census day.

Since the first Census Redistricting Data Program, conducted as part of the 1980 census, the U.S. Census Bureau has included summaries for the major race groups specified by the Statistical Programs and Standards Office of the U.S. Office of Management and Budget (OMB) in Directive 15 (as issued in 1977 and revised in 1997). Originally, the tabulation groups included White, Black, American Indian/Alaska Native, and Asian/Pacific Islander, plus “some other race.” These race data were also cross-tabulated by Hispanic/Non-Hispanic origin. At the request of the state legislatures and the Department of Justice, for the 1990 Census Redistricting Data Program, voting age (18 years old and over) was added to the cross-tabulation of race and Hispanic origin. For the 2000 Census, these categories were revised to the current categories used today.

  • 2020
  • 2010
  • 2000

2020 Census Redistricting Data (P.L. 94-171) Summary Files

The 2020 Census Redistricting Data (P.L. 94-171) Summary Files in the Legacy Format were posted for FTP download, by state, on August 12, 2021 and released on data.census.gov with the full redistricting toolkit on September 16, 2021. Both releases contained the same data, only the format was different. 

The summary file tables include: 

  • P1. – Race 
  • P2. – Hispanic or Latino, and not Hispanic or Latino by Race 
  • 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 
  • P5. – Group Quarters Population by Major Group Quarters Type 
  • H1. – Occupancy Status (Housing) 

The 2020 Census Redistricting Data (P.L. 94-171) Summary File data are available for all 50 states, the District of Columbia, and the Commonwealth of Puerto Rico through data.census.gov and FTP download (in the Legacy Format). 

The 2020 Census State Redistricting Data (P.L. 94-171) Summary File Technical Documentation is available in English, and in Spanish specifically for Puerto Rico. The 2020 Census National Redistricting Data (P.L. 94-171) Summary File Technical Documentation is available in English only. Links to the Technical Documentation are provided below.

Legacy Format Support Materials are provided to help data users work with the legacy format summary files. These materials include header records for each of the data segments in the summary file, Microsoft Access shells, an instructional guide and video tutorial that provide step-by-step instructions on how to download the legacy format data and import the data into the Microsoft Access Shells, and SAS and R statistical software import scripts. Links to these support materials are provided below. 

2020 Census (P.L. 94-171) Geographic Support Products

web TIGER\Line Shapefiles
Use the 2020 Tab of the linked page.
web Block Assignment Files (BAFs)
Use the 2020 Tab of the linked page. BAFs are meant to be used in conjunction with the NLTs.
web Name Look-up Tables (NLTs)
Use the 2020 Tab of the linked page. NLTs are meant to be used in conjunction with the BAFs.
web 2010 to 2020 Tabulation Block Crosswalk Tables
Use the 2020 Tab of the linked page. Select Block Relationship Files.

Group Quarters Assistance

The Census Bureau published a Federal Register Notice on the Final 2020 Census Residence Criteria and Residence Situations on February 8, 2018. In the Notice, the Census Bureau stated we will continue the practice of counting prisoners at the correctional facility, to ensure that the concept of usual residence is interpreted and applied consistent with the intent of the Census Act of 1790. The Notice also stated the Census Bureau recognizes that some states have decided, or may decide in the future, to ‘move’ their group quarters (GQ) population (e.g. student, military, and prisoner population) to an alternate address for the purpose of redistricting. To assist those states, the Census Bureau is offering the use of a geocoding service. This service was updated with 2020 Census geographic data in January 2021, to assist states with their goals of reallocating GQ population for legislative redistricting.

Explaining the 2020 Census Redistricting Data

America Counts Story
We bring you data visualizations with new 2020 Census data for your state and county on: population, race and ethnicity, diversity, age and housing.
America Counts Story
8.2 Million People Counted at U.S. Group Quarters in the 2020 Census
The 2020 Census data released today provide counts of the group quarters population down to the block level for the first time in a decade.
America Counts Story
Adult Population Grew Faster Than Total Population From 2010 to 2020
The first detailed results of the 2020 Census released today show a nationwide shift in the age makeup of the U.S. population from 2010 to 2020.
America Counts Story
Improved Race, Ethnicity Measures Show U.S. is More Multiracial
Today’s release of 2020 Census data provides a new snapshot of the racial and ethnic composition of the country.
America Counts Story
U.S. Housing Vacancy Rate Declined in Past Decade
The percentage of housing units vacant in 2020 dropped to 9.7% from 11.4% in 2010, according to 2020 Census data released this week.
America Counts Story
What Do We Know About the Quality of 2020 Census Redistricting Data?
To assess the quality of the redistricting data released today, we compared 2020 Census to key data benchmarks.
America Counts Story
Growth in Housing Units Slowed in the Last Decade
The 2020 Census results released today provide a count of vacant and occupied housing units across the nation.
America Counts Story
2020 U.S. Population More Racially, Ethnically Diverse Than in 2010
2020 Census results released today allow us to measure the nation’s racial and ethnic diversity and how it varies at different geographic levels.
America Counts Story
More Than Half of U.S. Counties Were Smaller in 2020 Than in 2010
The U.S. Census Bureau today released the first 2020 Census population counts for counties, metropolitan and micropolitan statistical areas, and cities.
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Random Samplings Blog
Using Demographic Benchmarks to Help Evaluate 2020 Census Results
One of the primary methods of evaluating the quality of a census is comparing the results to other population benchmarks.

Random Samplings Blog
The Census Geocoder - Group Quarters Assistance
People living in group quarters, such as nursing homes, military barracks, and college/university student housing, are among the unique populations counted in the 2020 Census.

Random Samplings Blog
Improvements to the 2020 Census Race and Hispanic Origin Question Designs, Data Processing, and Coding Procedures
This blog discusses how we improved the census questions on race and Hispanic origin, also known as ethnicity, between 2010 and 2020.

Random Samplings Blog
How We Complete the Census When Demographic and Housing Characteristics Are Missing
Although we strive to obtain all demographic and housing data from every individual in the census, missing data are part of every census process.

Random Samplings Blog
Resources Available to Prepare for the 2020 Census Redistricting Data Release
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.

Directors Blog
Redistricting Data: What to Expect and When
Since releasing the apportionment results in April, we’ve had several teams working hard on the next set of 2020 Census data — the redistricting data.

Directors Blog
Datos para la redistribución legislativa: qué esperar y cuándo
Hemos tenido varios equipos trabajando arduamente en el próximo conjunto de datos del Censo 2020 : los datos de redistritación.

Random Samplings Blog
Timeline for Releasing Redistricting Data
We expect to deliver the redistricting data to the states and the public by Sept. 30, 2021.

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The Comprehensive Course for Accessing 2020 Census Redistricting Data
This all-levels course will demonstrate several methods to access these data.
How to Access 2020 Census Redistricting Data Files from the FTP Site
This all-levels course will teach you how access redistricting data.
Redistricting Data Through the Census Data API: Tables and Group Calls
Following a few core concepts and steps, you can learn how to extract 2020 P.L. 94-171 Redistricting Data using the Census Bureau's API.
Accessing 2020 Redistricting Data: Mapping Geographies
Learn how to map geographies using data.census.gov.
Redistricting Data Through the Census Data API: Single Estimates
Learn the core concepts and steps needed to extract 2020 P.L. 94-171 Redistricting Data using the Census Bureau's Application Programming Interface (API).
Accessing 2020 Redistricting Data: Census Blocks
Learn how to find 2020 P.L. 94-171 Redistricting data at the Census block level on data.census.gov.
Accessing 2020 Census Redistricting Data on data.census.gov
In this video tutorial, we show you various examples on how to access Redistricting Data to pull tables on housing population counts, apply filters, and more.
Accessing 2020 Redistricting Data: Customizing Your Table View
The "Customize Table" button on data.census.gov gives data users many options to change the way they view a data table on data.census.gov.
Accessing 2020 Redistricting Data: Hispanic or Latino Population
In this tutorial, we show you how to navigate the data platform to find 2020 Redistricting data tables on the Hispanic or Latino population.
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Additional 2020 Census Resources

Declarations filed in the case of Ohio v. Raimondo

In declarations filed in the case of Ohio v. Raimondo, the U.S. Census Bureau made clear that we could provide a legacy format redistricting data summary file to all states by mid-to-late August 2021, now realized as August 12. We also met our commitment to provide the full redistricting data toolkit by Sept. 30, 2021, with delivery on Sept. 16, 2021.

Page Last Revised - April 5, 2023
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