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For Immediate Release: Friday, March 29, 2019

2018 Census Test Complete, Prototype Redistricting File Sent to States

Press Release Number CB19-TPS.15

MARCH 29, 2019 — The U.S. Census Bureau delivered the Public Law 94-171 Redistricting Data File prototype to all 50 states, the District of Columbia, and Puerto Rico today as part of the final 2018 Census Test requirements. This milestone marks the successful completion of the 2018 Census Test.

The prototype data set allows the states to develop their redistricting systems prior to the official receipt of the 2020 Census P.L. 94-171 data and geographic support files, which are due to the states prior to April 1, 2021, one year after Census Day 2020.

Through the 2020 Redistricting Data Program, official liaisons from each state can provide input to those geographic areas traditionally indicated as necessary for redistricting (e.g., blocks and voting districts). These are the areas for which states wish to receive decennial census population counts for the purpose of redistricting. The Census Bureau does not perform redistricting on behalf of states.

Although the final design of the 2020 P.L. 94-171 Redistricting Summary File will not be decided until later this year, the file will contain data on voting age, race, ethnicity, occupancy status, and (new for the 2020 Census) group quarters for standard census tabulation areas (e.g., state, congressional district, state legislative district, American Indian area, county, city, town, census tract, census block group, and census block), and for voting districts if states provided them through the Redistricting Data Program.

This is the first 2020 Census data product to use the Census Bureau’s new disclosure avoidance methodology.

Increased computing power, widespread availability of data on people residing in the United States, and advances in the mathematics have made it easier to learn private information about individuals from aggregated statistics. Recognizing this challenge, the Census Bureau developed a new privacy protection methodology. Before a statistic is published, statistical safeguards are applied that help prevent connecting a statistic to a specific respondent.

The 2018 Disclosure Avoidance System employs complex mathematical algorithms that inject carefully structured “random noise” into published tabulations. This system does not allow final published tabulations to depend on any one person’s data, and so will not reveal private information about any individual.

The data provided in the prototype file are not official numbers and are not suitable to use for redistricting, funding, or planning purposes related to Providence County, Rhode Island. We are releasing the prototype to allow stakeholders an opportunity to review the Census Bureau’s tabulation plans and product suite prior to the 2020 Census.


No news release associated with this product. Tip Sheet only.


Kristina Barrett
Public Information Office


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