The U.S. Census counts every resident in the United States. It is mandated by Article I, Section 2 of the Constitution and takes place every 10 years. The data collected by the decennial census determine the number of seats each state has in the U.S. House of Representatives and is also used to distribute billions in federal funds to local communities.
Census Data shows Contra Costa County has 1,049,025 residents in 2010.
The County grew by 100,209 residents or 10.6% making Contra Costa the fastest growing County in the Bay Area.
California State Department of Finance has summary tables
available that show the change in population and housing characteristics.
The Census Bureau has all the 2010 Data available onlinevia their American FactFinder