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The original item was published from 8/13/2021 2:25:11 PM to 8/13/2021 2:26:38 PM.

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Posted on: August 13, 2021

[ARCHIVED] U.S. Census Bureau Releases First Local 2020 Census Data

Redistricting Map and URL

The U.S. Census Bureau has released the first local level data from the 2020 Census, the once-a-decade count of every person living in the country. This is part of the Census data that will help determine new Supervisorial districts for Contra Costa County during its Redistricting process.

The Census data release provides the first look at the demographic characteristics at the local level, including population change, race, ethnicity, age 18 and over population, and housing occupancy status.

The data shows Contra Costa County’s population has increased by 10% or 116,902 people, since the 2010 Census, for a total population of 1,165,927. The 2020 Census data indicates that Contra Costa County has become increasingly diverse and multiracial.

The following charts show growth and race/ethnicity breakdown by Supervisorial District:

Bar chart showing 2010 to 2020 Population Growth by Supervisorial District

Population by Supervisorial District and Deviation from Mean                             

Districts must be redrawn so that each district is substantially equal in population.

Equal Proportion based on 2020 Census: 233,185 people.
The current spread is 8.08%, this is the difference between the highest and lowest percentage from the mean.
The percentage deviation from the mean is shown in parenthesis below. 

District 1 Population: 224,726
8,459 under (-3.63%)

District 2 Population: 243,565
10,380 over (4.45%)

District 3 Population: 239,825
6,640 over (2.85%)

District 4 Population: 229,384
3,837 under (-1.65%)

District 5 Population: 228,463
4,722 under (-2.03%)

Race and Ethnicity by Supervisorial District

Bar chart showing Diversity statistics Countywide and within each Supervisorial district.

This information shows how the ethnic, racial, and voting age makeup of neighborhoods has changed since the 2010 Census. The local level results for Contra Costa are available on the County’s dedicated Redistricting website, With this data, the public will now be able to draw their Communities of Interest proposals and submit them on this County website.

The actual drawing of Supervisorial District Maps requires the official California State Adjusted Redistricting data, which is expected to be available in September 2021, and will include updated data to ensure incarcerated individuals are counted by each jurisdiction.

“The release of the local data from the 2020 Census forms the basis for the Redistricting process in Contra Costa County,” said Board Chair, Supervisor Diane Burgis. “We want to thank all of the Complete Count committee members, community partners, community-based organizations, and volunteers who worked so hard to get a complete Census count for our County. The Board of Supervisors and I look forward to engaging and encouraging the public to provide valuable input in our County’s selection of supervisorial district maps.”

What is Redistricting?
Every ten years, Supervisorial districts must be redrawn so that each district is substantially equal in population. Redistricting determines which neighborhoods and communities are grouped together into a district for purposes of electing a board member. The Board of Supervisors will seek input in selecting the next district map for supervisorial districts in Contra Costa County.

Contra Costa County Board of Supervisors is committed to a robust public outreach effort, including public hearings, community workshops, email updates, and a resource rich website that includes easy-to-use online mapping tools.

See Press Release (PDF).

For more information about Redistricting and how to provide input, visit or the County website’s homepage at  

Learn more about Redistricting in Contra Costa.

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