Contra Costa’s population stood at 1,049,025 as per the 2010 census. Land in Contra Costa County, California, was diversified at that time, which many ethnic groups represented. The county's racial makeup was 58.6% White, 9.3% Black or African Americans, 0.6% Native American, 14.4% Asian, 2.1% Indian, 3.8% Chinese, and 4.6% Filipino. There were about 24.4% of people of Latino or Hispanic ancestry. People with Mexican heritage made up 17.2% of the population, while 1.9% had Salvadoran heritage.
In the 2000 census, Contra Costa County had 344,129 households, out of which 35% had children aged under 18 years living there. 29.6% of the households were non-families, 54.5% were married couples living together, and 11.5% had a female holder with no husband. Around 22.8% of households in the county were made up of individuals, and 8% of them had people aged above 65 years. The average family size was 3.23, and the average household size was 2.72.
The median income for a household in Contra Costa County was $63,675, which was the highest in the state of California. The median income for a family was $73,038 in 2002, which rose to $87,435 in 2007. The significant increase in the income median is attributed to the thriving economy in Contra Costa County and California at large. This growth has made land for sale in Contra Costa County, California, highly valuable. The male's median income in the census was $52,670, while females had a median income of $30,615. About 5.2% of families and 7.2% of the population lived below the poverty line.