Castle Hill, California Demographics & Population 2026

Population Overview

Castle Hill is a small community located in California, within Contra Costa County. The total population is 1,026. It ranks as the 1057th most populous out of 1,570 Census-designated places in California.

Age Demographics

The median age in Castle Hill is 43.9 years. This is 16% higher than the state median of 37.9 years. With 30.8% of the population under 18, Castle Hill has a notably young demographic profile, suggesting a family-oriented community.

Economy, Income & Housing

The median household income in Castle Hill is $250,000+. This is 152% higher than the state median of $99,122. It is also 210% higher than the national median of $80,734. The poverty rate stands at 0.2%. This is 98% lower than the state poverty rate of 12.0%. This exceptionally low poverty rate indicates strong economic prosperity across the community. The survey records no unemployed residents in Castle Hill, which reflects the size of the sample rather than a labor market without joblessness. The median home value is $2,000,000+. Housing costs are 172% higher than the state median of $734,700. The home-value-to-income ratio of 8.0x suggests that housing affordability is a significant concern for many residents. 91.2% of occupied housing units are owner-occupied. This homeownership rate is 63% higher than the state average of 55.9%.

Race & Ethnicity

The largest racial or ethnic group in Castle Hill is White (non-Hispanic), making up 72.3% of the population. Asian residents account for 15.7%. The White (non-Hispanic) population is significantly higher than the state average (72.3% vs 33.8%).

Education

79.5% of residents aged 25 and older hold a bachelor's degree or higher. This places Castle Hill in the top 10% of all cities in the state for educational attainment. This is 114% higher than the state rate of 37.1%. Nationally, 35.7% of adults hold at least a bachelor's degree. No surveyed resident aged 25 or older reported leaving school before earning a high school diploma, though a rate of exactly 100% reflects the limits of a small sample. Notably, 27.6% of adults hold a graduate or professional degree, indicating a highly educated workforce.

Data Sources & Methodology

All demographic data for Castle Hill, California is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. Comparisons are made against California state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 1,570 Census-designated places in California. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.