| | Atherton, CA | Rocklin, CA | United States |
| Population | 7,181 | 70,317 | 329,725,481 |
| Female Population | 50.1% | 50.8% | 50.5% |
| Male Population | 49.9% | 49.2% | 49.5% |
| Median Age | 47.9 | 37.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 6,932 | 57,482 | 309,327,143 |
| Population - 2000 | 7,194 | 36,330 | 285,036,114 |
| Population - 1990 | 7,163 | 19,033 | 251,960,433 |
| Pop. 2000 to Now | -2.5% | 93.1% | 15.6% |
| Pop. 1990 to Now | -2.1% | 268.6% | 30.8% |
| space4 | | | |
| Population Density | 1,427.6 | 3,549.6 | 93.4 |
| Land Area | 5.0 | 19.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Atherton, CA | Rocklin, CA | United States |
| Age 0 to 4 | 2.1% | 5.9% | 5.9% |
| Age 5 to 9 | 3.3% | 7.2% | 6.1% |
| Age 10 to 14 | 9.1% | 8.1% | 6.6% |
| Age 15 to 17 | 5.9% | 5.0% | 3.9% |
| Age 18 to 20 | 8.4% | 4.2% | 4.0% |
| Age 21 to 24 | 4.5% | 5.5% | 5.2% |
| Age 25 to 34 | 7.1% | 10.8% | 13.8% |
| Age 35 to 44 | 6.8% | 15.2% | 12.9% |
| Age 45 to 54 | 15.3% | 13.6% | 12.6% |
| Age 55 to 59 | 7.9% | 6.0% | 6.7% |
| Age 60 to 64 | 5.7% | 4.8% | 6.3% |
| Age 65 to 74 | 12.6% | 8.0% | 9.6% |
| Age 75 to 84 | 6.9% | 4.1% | 4.5% |
| Age 85 and over | 4.5% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Atherton, CA | Rocklin, CA | United States |
| White | 67.9% | 66.6% | 59.4% |
| Black | 1.2% | 1.7% | 12.2% |
| Asian | 18.6% | 11.0% | 5.6% |
| Native American | 0.1% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.4% | 0.2% | 0.2% |
| Other | 0.0% | 0.7% | 0.4% |
| Two or More Races | 3.1% | 5.6% | 3.2% |
| Hispanic | 8.8% | 13.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Atherton, CA | Rocklin, CA | United States |
| Married Population | 58.9% | 57.7% | 49.8% |
| Currently Married | 58.3% | 56.6% | 48.0% |
| Married but Separated | 0.6% | 1.1% | 1.8% |
| Single Population | 41.1% | 42.3% | 50.2% |
| Never Married | 33.3% | 28.8% | 33.8% |
| Divorced | 3.4% | 9.1% | 10.8% |
| Widowed | 4.4% | 4.4% | 5.6% |
| space5 | | | |
| Household Size | 2.92 | 2.86 | 2.60 |
| Households | 2,244 | 24,179 | 124,010,992 |
| Family Households | 1,843 | 17,660 | 80,755,759 |
| Married couple, w/children | 35.7% | 44.5% | 30.5% |
| Married couple, no children | 55.9% | 39.2% | 42.9% |
| Non Family Households | 401 | 6,519 | 43,255,233 |
| Single householder, w/children | 5.1% | 8.5% | 15.8% |
| Single householder, no children | 3.3% | 7.8% | 10.8% |