Rossmoor, CA has a population of 10,933 and is the 3,688th largest city in the United States. The population density is 7,084 per sq mi which is 2948% higher than the California average and 7719% higher than the national average. The median age in Rossmoor is 46 which is approximately 27% higher than the California average of 36. In Rossmoor, 68% of the population over 15 years of age are married, 86% speak English and 3% speak Spanish. 67% of Rossmoor residents were born in California, 21% were born out of state, 1% were born outside of the United States and 11% were foreign born.