Castle Hill, CA has a population of 1,202 and is the 14,022nd largest city in the United States. The population density is 1,653 per sq mi which is 611% higher than the California average and 1724% higher than the national average. The median age in Castle Hill is 51 which is approximately 41% higher than the California average of 36. In Castle Hill, 54% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 63% of Castle Hill residents were born in California, 32% were born out of state, 0% were born outside of the United States and 5% were foreign born.