| | Morro Bay, CA | Castaic, CA | United States |
| Population | 10,785 | 18,017 | 329,725,481 |
| Female Population | 51.2% | 50.0% | 50.5% |
| Male Population | 48.8% | 50.0% | 49.5% |
| Median Age | 51.3 | 38.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 10,256 | 18,134 | 309,327,143 |
| Population - 2000 | 10,350 | 18,001 | 285,036,114 |
| Population - 1990 | 9,664 | 7,647 | 251,960,433 |
| Pop. 2000 to Now | 2.0% | 5.8% | 15.6% |
| Pop. 1990 to Now | 9.3% | 149.0% | 30.8% |
| space4 | | | |
| Population Density | 2,025.7 | 2,481.0 | 93.4 |
| Land Area | 5.3 | 7.3 | 3,531,905.4 |
| Water Area | 5.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Morro Bay, CA | Castaic, CA | United States |
| Age 0 to 4 | 3.6% | 6.5% | 5.9% |
| Age 5 to 9 | 3.0% | 6.5% | 6.1% |
| Age 10 to 14 | 3.5% | 8.1% | 6.6% |
| Age 15 to 17 | 3.7% | 4.5% | 3.9% |
| Age 18 to 20 | 4.6% | 3.0% | 4.0% |
| Age 21 to 24 | 3.0% | 4.2% | 5.2% |
| Age 25 to 34 | 12.1% | 13.4% | 13.8% |
| Age 35 to 44 | 10.1% | 12.5% | 12.9% |
| Age 45 to 54 | 12.1% | 15.2% | 12.6% |
| Age 55 to 59 | 8.2% | 9.2% | 6.7% |
| Age 60 to 64 | 7.7% | 6.1% | 6.3% |
| Age 65 to 74 | 17.9% | 7.5% | 9.6% |
| Age 75 to 84 | 8.4% | 2.5% | 4.5% |
| Age 85 and over | 2.2% | 0.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Morro Bay, CA | Castaic, CA | United States |
| White | 74.5% | 49.0% | 59.4% |
| Black | 0.2% | 1.7% | 12.2% |
| Asian | 5.3% | 11.9% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 1.7% | 1.1% | 0.4% |
| Two or More Races | 3.1% | 7.3% | 3.2% |
| Hispanic | 15.0% | 28.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Morro Bay, CA | Castaic, CA | United States |
| Married Population | 50.1% | 59.6% | 49.8% |
| Currently Married | 47.0% | 58.5% | 48.0% |
| Married but Separated | 3.1% | 1.2% | 1.8% |
| Single Population | 49.9% | 40.4% | 50.2% |
| Never Married | 29.2% | 28.3% | 33.8% |
| Divorced | 13.2% | 7.0% | 10.8% |
| Widowed | 7.5% | 5.1% | 5.6% |
| space5 | | | |
| Household Size | 2.18 | 3.19 | 2.60 |
| Households | 4,884 | 5,656 | 124,010,992 |
| Family Households | 2,724 | 4,727 | 80,755,759 |
| Married couple, w/children | 24.5% | 41.3% | 30.5% |
| Married couple, no children | 54.8% | 41.1% | 42.9% |
| Non Family Households | 2,160 | 929 | 43,255,233 |
| Single householder, w/children | 9.3% | 6.5% | 15.8% |
| Single householder, no children | 11.4% | 11.1% | 10.8% |