| | Fairfax Station, VA | San Clemente, CA | United States |
| Population | 12,322 | 64,600 | 329,725,481 |
| Female Population | 50.0% | 49.3% | 50.5% |
| Male Population | 50.1% | 50.7% | 49.5% |
| Median Age | 44.6 | 43.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 11,708 | 63,556 | 309,327,143 |
| Population - 2000 | 12,098 | 49,936 | 285,036,114 |
| Population - 1990 | 11,460 | 41,100 | 251,960,433 |
| Pop. 2000 to Now | -3.2% | 29.3% | 15.6% |
| Pop. 1990 to Now | 2.2% | 57.1% | 30.8% |
| space4 | | | |
| Population Density | 1,356.9 | 3,519.3 | 93.4 |
| Land Area | 9.1 | 18.4 | 3,531,905.4 |
| Water Area | 0.1 | 0.8 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Fairfax Station, VA | San Clemente, CA | United States |
| Age 0 to 4 | 4.3% | 4.7% | 5.9% |
| Age 5 to 9 | 4.3% | 5.3% | 6.1% |
| Age 10 to 14 | 8.1% | 7.6% | 6.6% |
| Age 15 to 17 | 4.6% | 4.9% | 3.9% |
| Age 18 to 20 | 3.9% | 2.6% | 4.0% |
| Age 21 to 24 | 5.2% | 3.6% | 5.2% |
| Age 25 to 34 | 9.7% | 10.7% | 13.8% |
| Age 35 to 44 | 10.8% | 11.9% | 12.9% |
| Age 45 to 54 | 15.5% | 14.9% | 12.6% |
| Age 55 to 59 | 8.3% | 8.0% | 6.7% |
| Age 60 to 64 | 7.5% | 7.2% | 6.3% |
| Age 65 to 74 | 11.9% | 10.8% | 9.6% |
| Age 75 to 84 | 5.0% | 5.5% | 4.5% |
| Age 85 and over | 1.0% | 2.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Fairfax Station, VA | San Clemente, CA | United States |
| White | 70.9% | 72.9% | 59.4% |
| Black | 4.0% | 1.5% | 12.2% |
| Asian | 13.8% | 5.0% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.3% | 0.2% | 0.4% |
| Two or More Races | 3.8% | 3.8% | 3.2% |
| Hispanic | 7.2% | 16.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Fairfax Station, VA | San Clemente, CA | United States |
| Married Population | 61.2% | 60.0% | 49.8% |
| Currently Married | 60.8% | 58.9% | 48.0% |
| Married but Separated | 0.4% | 1.1% | 1.8% |
| Single Population | 38.8% | 40.0% | 50.2% |
| Never Married | 29.6% | 25.9% | 33.8% |
| Divorced | 6.3% | 9.2% | 10.8% |
| Widowed | 2.9% | 4.9% | 5.6% |
| space5 | | | |
| Household Size | 2.99 | 2.68 | 2.60 |
| Households | 4,114 | 24,006 | 124,010,992 |
| Family Households | 3,360 | 17,141 | 80,755,759 |
| Married couple, w/children | 36.3% | 34.0% | 30.5% |
| Married couple, no children | 54.2% | 51.2% | 42.9% |
| Non Family Households | 754 | 6,865 | 43,255,233 |
| Single householder, w/children | 4.5% | 9.1% | 15.8% |
| Single householder, no children | 5.0% | 5.7% | 10.8% |