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The Commemorative
Quarter for
The Commemorative Quarter for California

Time Zone: Contra Costa County lies in the Pacific Time Zone (PST/PDT) and observes daylight saving time.

The community of Martinez is the Seat for Contra Costa County.

Contra Costa County is one of the original counties of California and was founded in 1850.

From the Census Estimates for 2009, <1> Contra Costa had a population of 1,041,274 people. This is an increase of 9.74% since the last Census (which gave a population of 948,816 people in 2000).

At the time of the 2000 Census, Contra Costa represented 2.8% of the total population of California, making it the state's 9th most populous county (out of 58 counties).

The following table shows the recent changes in population. Other than 2000, the population counts have been estimated by the Census Bureau.

Since 2000
Year-to-Year Change
20101,049,025+10.56%+0.74% since 2009
20091,041,274+9.74%+1.54% since 2008
20081,025,464+8.08%+1.48% since 2007
2000948,816The Last Census

More information can be found on the Contra Costa County Census Page for Contra Costa County.


Below are some of the communities located in Contra Costa County (for more communities, please visit our Nearby Page for Contra Costa County):

Community 2009
(2009vs. 2000)
Concord   122,224121,7800.36% increase  
Richmond   103,16599,2163.98% increase  
Antioch   101,18190,53211.76% increase  
Pittsburg   65,12856,76914.72% increase  
Walnut Creek   64,00764,2960.45% decrease  

Websites for Contra Costa County

Official Website:   www.co.contra-costa.ca.us/

If you know of a history or genealogy society whose interest includes Contra Costa County, would you please send us the URL for their website? We would like to add their link to our Gazetteer. To contact us, please visit our Feedback Page.

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Footnotes ...

<1>On a yearly basis, the US Census Bureau creates an estimate of the county's population. Keep in mind that this is an estimate and not an actual count. The last physical count was the 2000 Census and the next count will be for the 2010 Census.

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<2>All Quarter-dollar coin images from the United States Mint.

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