| | Dahlgren, VA | Annandale, VA | United States |
| Population | 3,448 | 41,869 | 329,725,481 |
| Female Population | 48.1% | 51.6% | 50.5% |
| Male Population | 51.9% | 48.4% | 49.5% |
| Median Age | 34.1 | 38.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,345 | 38,439 | 309,327,143 |
| Population - 2000 | 997 | 54,994 | 285,036,114 |
| Population - 1990 | 1,611 | 50,975 | 251,960,433 |
| Pop. 2000 to Now | 237.2% | -18.4% | 15.6% |
| Pop. 1990 to Now | 108.7% | -11.9% | 30.8% |
| space4 | | | |
| Population Density | 1,288.0 | 5,335.0 | 93.4 |
| Land Area | 2.7 | 7.8 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Dahlgren, VA | Annandale, VA | United States |
| Age 0 to 4 | 3.9% | 6.5% | 5.9% |
| Age 5 to 9 | 6.8% | 5.7% | 6.1% |
| Age 10 to 14 | 7.8% | 6.5% | 6.6% |
| Age 15 to 17 | 4.9% | 3.2% | 3.9% |
| Age 18 to 20 | 4.1% | 3.6% | 4.0% |
| Age 21 to 24 | 8.7% | 4.8% | 5.2% |
| Age 25 to 34 | 16.2% | 14.6% | 13.8% |
| Age 35 to 44 | 16.0% | 13.8% | 12.9% |
| Age 45 to 54 | 7.9% | 11.1% | 12.6% |
| Age 55 to 59 | 3.7% | 7.7% | 6.7% |
| Age 60 to 64 | 7.8% | 6.4% | 6.3% |
| Age 65 to 74 | 8.6% | 10.0% | 9.6% |
| Age 75 to 84 | 2.6% | 3.9% | 4.5% |
| Age 85 and over | 1.0% | 2.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Dahlgren, VA | Annandale, VA | United States |
| White | 56.7% | 33.4% | 59.4% |
| Black | 28.0% | 8.3% | 12.2% |
| Asian | 0.3% | 22.8% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 1.3% | 0.3% | 0.4% |
| Two or More Races | 6.4% | 3.1% | 3.2% |
| Hispanic | 7.3% | 31.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Dahlgren, VA | Annandale, VA | United States |
| Married Population | 54.7% | 50.0% | 49.8% |
| Currently Married | 54.3% | 48.1% | 48.0% |
| Married but Separated | 0.4% | 1.9% | 1.8% |
| Single Population | 45.3% | 50.0% | 50.2% |
| Never Married | 34.4% | 35.2% | 33.8% |
| Divorced | 6.5% | 9.5% | 10.8% |
| Widowed | 4.5% | 5.4% | 5.6% |
| space5 | | | |
| Household Size | 2.70 | 2.97 | 2.60 |
| Households | 1,278 | 13,923 | 124,010,992 |
| Family Households | 910 | 9,938 | 80,755,759 |
| Married couple, w/children | 37.5% | 30.4% | 30.5% |
| Married couple, no children | 41.3% | 37.7% | 42.9% |
| Non Family Households | 368 | 3,985 | 43,255,233 |
| Single householder, w/children | 16.9% | 16.9% | 15.8% |
| Single householder, no children | 4.3% | 14.9% | 10.8% |