2020 Census

Dates, Details, and Updates – 2020 Census

Important Dates


Date Event
September 2024 (Planned) Detailed Demographic and Housing Characteristics File B (Detailed DHC-B).
September 2024 (Planned) Supplemental Demographic and Housing Characteristics File (S-DHC)

Note: Dates are subject to change.


Date Event
March 2, 2023 Final date to submit feedback on the Detailed DHC-A Proof of Concept. Details can be found on the 2020 Census Developing the DAS page.
April 12, 2023 Final date to submit comments on proposed updates to federal race and ethnicity statistical standards. Access the Federal Register Notice.
May 25, 2023 Demographic and Housing Charactertics (DHC) File and Demographic Profiles Release
June 30, 2023 Deadline for governments to send CQR cases to the Census Bureau
Deadline for governments to send PCGQR cases to the Census Bureau
August 2023 (Planned) Congressional District Summary Files Release
September 2023 (Planned) Detailed DHC-A Release
September 30, 2023 Deadline for the Census Bureau to provide CQR results to impacted governmental units

Note: Dates are subject to change.


Date Event
January 2022 The Census Bureau begins accepting CQR cases for processing from eligible tribal, state and local governments
May 1, 2022 State, county, and city population estimates as of January 1, 2022, using 2020 Census data

Note: Dates are subject to change.


Date Event
April 26, 2021 2020 Census state apportionment counts released
August 12, 2021 2020 Census local redistricting data (P.L. 94-171), “Legacy” format
September 16, 2021 2020 Census local redistricting data (P.L. 94-171), tabular format
Fall 2021 (proposed) Count Question Resolution (CQR) Program – Federal Register notice announces the beginning of a 30-day comment period for the public
December 2021 State and county population estimates for July 1, 2021, using 2020 Census data
December 2021 The Census Bureau plans to officially notify tribal, state and local government officials eligible to file CQR cases
December 15, 2021 Deadline for new California Congressional, Assembly, and Senate district maps

Note: Dates are subject to change.

Apportionment and Redistricting Data


The Demographic Research Unit has published tabulations and maps derived from the 2020 Census P.L. 94-171 data set released on August 12.  These tabulations and maps along with other data products can be found on our Census 2020 Data page.

The Redistricting File (Public Law 94-171) or P.L. 94-171 file, contains the census block level data needed by state and local governments to re-draw their local districts based on the 2020 Census data. This file was released on August 12, 2021. The data in this file includes:

  • Population data: total, 18 years and older, race and Hispanic origin
  • Housing Unit data: total, occupied, vacant
  • Group Quarter population by type of group quarters

The Geographic Support Products, including maps, GIS shape files, and crosswalk files, for the 2020 Census P.L. 94-171 file are now available online.

In California, statewide redistricting is done by the California Citizens Redistricting Commission that draws new Congressional, state Senate, Assembly, and Board of Equalization district boundaries. The Commission will establish boundaries based on 2020 Census data with the help of the Statewide Database, at the University of California, Berkeley. The deadline for this process is December 15, 2021.


The U.S. Census Bureau released the 2020 Census Apportionment counts on April 26, 2021. The results for California are:

  2020 2010 % Change
Total Resident Population 39,538,223 37,253,956 6.1%
Total Overseas Population 38,534 88,033 -56.2%
Number of Seats in the House of Representatives 52 53 NA

Historical California total population and U.S. House of Representative seats: 1850-2020.

For details on the initial release of the 2020 Census counts, please click on one of the links below.

“Apportionment” is the process of dividing the 435 seats in the House of Representatives among the 50 states. Results from the 2020 Census will be the base population for this process. Learn more about Apportionment at the U.S. Census Bureau website.

2020 Count Question Resolution (CQR)

The 2020 Census Count Question Resolution program provides a mechanism for state, local and tribal governments to request a review of their official 2020 Census results. In the past, CQR allowed corrections to population and housing counts due to boundary, geocoding, and certain coverage issues. Information about the CQR program can be found at the Census Bureau CQR page.

In support of the 2020 CQR operation, the DRU has produced the California CQR Explorer to help identify areas of concern. We hope to increase participation in the 2020 CQR operation by empowering jurisdictions that may lack the time, technology, or staff to research potential CQR cases and provide them with pre-generated cases and supplementary material.

As a result of the 2010 Census CQR, U.S. total population count increased by 527 people and the number of housing units increased by 224 while State of California total population and housing counts did not change. See a list of California governmental units that submitted challenges.

2020 Post-Census Group Quarter Review (PCGQR)

The 2020 Post-Census Group Quarters Review is a new, one-time operation for eligible governmental entities (tribal areas, states, counties, minor civil divisions, consolidated cities, and incorporated places) to request a review by the Census Bureau of population counts of groups quarters (college dormitories, correctional facilities, etc.) they believe were not correctly counted in the 2020 Census. Updated population counts resulting from the 2020 PCGQR will be used to inform and improve Census Bureau’s population estimates and other statistics but it will not change or update 2020 Census counts or data products. Further information can be found on the Census Bureau PCGQR page.

The DRU has created the California PCGQR explorer to assist with identifying areas of concern regarding group quarters facilities and populations. Communities can use the map to help assess whether GQ facilities were counted, and resident populations were enumerated at their place of “usual residence” on April 1, 2020.

Disclosure Avoidance

The U.S. Census Bureau has a long history of protecting decennial census responses. For the 2020 Census, the Bureau plans to implement differential privacy (DP), a disclosure avoidance method that provides a mathematical limit on the increased risk of being included versus not included in the data set. DP protects privacy by infusing noise into the data.

The Census Bureau’s Data Stewardship Executive Policy Committee (DSEP) has finalized the list of invariants, or statistics that will be published without noise infusion, for the 2020 Census data products. The following statistics will be invariant at these geographic levels and higher:

  • Total population (at the nation, state, and state-equivalent level, for example, the District of Columbia and Puerto Rico)
  • Total housing units (at the census block level)
  • Number of group quarters facilities by type (at the census block level)

2020 Census Data Evaluation

  • Demographic Analysis
    Demographic Analysis (DA) is one of the ways the U.S. Census Bureau will evaluate the quality of 2020 Census. The DA method uses vital records, data on international migration, and Medicare records, and provides population totals to compare against 2020 Census results. The Bureau released DA national estimates by age, sex, certain race categories, and Hispanic origin on December 15, 2020. DA estimate for total U.S. population as of April 1, 2020 is 332.6 million (middle series), and varies from 330.7 million (low series) to 335.5 million (high series). Experimental DA state and county estimates for the population ages 0-4 are expected to be released in 2022.
  • Post-Enumeration Survey
    The Post-Enumeration Survey, which is conducted immediately after census operations are completed, is used by the U.S. Census Bureau to estimate the under- or over-count by demographic group and geography. The first results are expected to be released at the end of December 2021.
  • Review of Methods and Procedures
    The U.S. Census Bureau has asked outside groups of experts to provide assessments of the methods and procedures employed in the 2020 Census. These groups include:
    JASON is an independent group of scientists and engineers with expertise in a variety of technical areas related to the Census. JASON’s goal was to identify strengths and weaknesses in Census Bureau plans for data quality assessments and metrics, and to improve communication of important aspects of data quality that could accompany release of 2020 Census data products. Its report can be accessed here.
  • The American Statistical Association (ASA)
    The ASA has assisted the Census Bureau with research and development of operational aspects of past censuses. It released an initial report in October 2020 entitled 2020 Census Quality Indicators, which was recently updated. The ASA also has published a timeline of updates to the report.
  • California Neighborhoods Count Report
    On Sept. 20, 2022 the RAND Corporation released the “2020 California Neighborhoods Count” report, an independent survey to evaluate the accuracy of the 2020 census in California. The DRU prepared a separate “Overview of CNC responses related to California Complete Count – Census 2020.

California Complete Count – Census 2020

California launched a statewide effort to ensure an accurate and complete count of Californians in the 2020 Census. The California Complete Count – Census 2020 Office coordinated the State’s outreach and communication strategy, which focused on the hardest-to-count residents. Working through local governments, Tribal Governments, community-based organizations and media, the state funded work that complemented work that was done nationally by the U.S. Census Bureau. The California Census Office offers online maps with hard-to-count population and self-response rates.

Comments, suggestions, or questions? Please email CensusData4CA@dof.ca.gov.