| | Rio del Mar, CA | Aptos, CA | United States |
| Population | 9,264 | 6,372 | 329,725,481 |
| Female Population | 50.6% | 56.9% | 50.5% |
| Male Population | 49.4% | 43.1% | 49.5% |
| Median Age | 50.1 | 53.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 9,422 | 6,255 | 309,327,143 |
| Population - 2000 | 9,198 | 9,396 | 285,036,114 |
| Population - 1990 | 8,919 | 9,061 | 251,960,433 |
| Pop. 2000 to Now | 3.2% | -39.3% | 15.6% |
| Pop. 1990 to Now | 6.5% | -37.1% | 30.8% |
| space4 | | | |
| Population Density | 3,088.0 | 968.7 | 93.4 |
| Land Area | 3.0 | 6.6 | 3,531,905.4 |
| Water Area | 1.6 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Rio del Mar, CA | Aptos, CA | United States |
| Age 0 to 4 | 3.0% | 2.0% | 5.9% |
| Age 5 to 9 | 4.8% | 3.9% | 6.1% |
| Age 10 to 14 | 7.7% | 2.7% | 6.6% |
| Age 15 to 17 | 3.0% | 2.0% | 3.9% |
| Age 18 to 20 | 4.7% | 8.7% | 4.0% |
| Age 21 to 24 | 4.5% | 4.5% | 5.2% |
| Age 25 to 34 | 4.3% | 12.9% | 13.8% |
| Age 35 to 44 | 10.3% | 3.8% | 12.9% |
| Age 45 to 54 | 15.0% | 11.3% | 12.6% |
| Age 55 to 59 | 10.5% | 10.9% | 6.7% |
| Age 60 to 64 | 9.1% | 13.3% | 6.3% |
| Age 65 to 74 | 12.4% | 14.3% | 9.6% |
| Age 75 to 84 | 6.3% | 7.1% | 4.5% |
| Age 85 and over | 4.4% | 2.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Rio del Mar, CA | Aptos, CA | United States |
| White | 78.9% | 78.9% | 59.4% |
| Black | 0.4% | 0.5% | 12.2% |
| Asian | 1.9% | 3.4% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.8% | 0.0% | 0.4% |
| Two or More Races | 5.7% | 3.6% | 3.2% |
| Hispanic | 12.3% | 13.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Rio del Mar, CA | Aptos, CA | United States |
| Married Population | 58.3% | 49.3% | 49.8% |
| Currently Married | 58.1% | 48.4% | 48.0% |
| Married but Separated | 0.2% | 0.9% | 1.8% |
| Single Population | 41.7% | 50.7% | 50.2% |
| Never Married | 24.0% | 33.4% | 33.8% |
| Divorced | 12.6% | 9.8% | 10.8% |
| Widowed | 5.1% | 7.5% | 5.6% |
| space5 | | | |
| Household Size | 2.41 | 2.43 | 2.60 |
| Households | 3,843 | 2,621 | 124,010,992 |
| Family Households | 2,663 | 1,838 | 80,755,759 |
| Married couple, w/children | 21.8% | 15.7% | 30.5% |
| Married couple, no children | 60.1% | 53.4% | 42.9% |
| Non Family Households | 1,180 | 783 | 43,255,233 |
| Single householder, w/children | 9.2% | 7.5% | 15.8% |
| Single householder, no children | 8.9% | 23.4% | 10.8% |