| | Marietta, PA | Blackstone, VA | United States |
| Population | 2,694 | 3,402 | 329,725,481 |
| Female Population | 45.6% | 58.1% | 50.5% |
| Male Population | 54.4% | 41.9% | 49.5% |
| Median Age | 41.7 | 45.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,589 | 3,606 | 309,327,143 |
| Population - 2000 | 2,689 | 3,675 | 285,036,114 |
| Population - 1990 | 2,778 | 3,497 | 251,960,433 |
| Pop. 2000 to Now | -3.7% | -10.1% | 15.6% |
| Pop. 1990 to Now | -6.8% | -5.5% | 30.8% |
| space4 | | | |
| Population Density | 3,606.4 | 756.8 | 93.4 |
| Land Area | 0.7 | 4.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Marietta, PA | Blackstone, VA | United States |
| Age 0 to 4 | 9.2% | 4.2% | 5.9% |
| Age 5 to 9 | 5.0% | 3.1% | 6.1% |
| Age 10 to 14 | 2.8% | 8.3% | 6.6% |
| Age 15 to 17 | 2.3% | 6.7% | 3.9% |
| Age 18 to 20 | 1.5% | 3.6% | 4.0% |
| Age 21 to 24 | 2.4% | 5.6% | 5.2% |
| Age 25 to 34 | 17.4% | 8.1% | 13.8% |
| Age 35 to 44 | 13.5% | 8.5% | 12.9% |
| Age 45 to 54 | 14.1% | 13.2% | 12.6% |
| Age 55 to 59 | 5.2% | 6.6% | 6.7% |
| Age 60 to 64 | 5.7% | 12.3% | 6.3% |
| Age 65 to 74 | 15.9% | 7.4% | 9.6% |
| Age 75 to 84 | 3.8% | 4.5% | 4.5% |
| Age 85 and over | 1.3% | 8.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Marietta, PA | Blackstone, VA | United States |
| White | 78.9% | 41.2% | 59.4% |
| Black | 3.3% | 47.2% | 12.2% |
| Asian | 0.3% | 0.9% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 8.4% | 0.0% | 0.4% |
| Two or More Races | 1.1% | 0.8% | 3.2% |
| Hispanic | 8.0% | 10.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Marietta, PA | Blackstone, VA | United States |
| Married Population | 58.0% | 42.5% | 49.8% |
| Currently Married | 56.7% | 39.0% | 48.0% |
| Married but Separated | 1.3% | 3.5% | 1.8% |
| Single Population | 42.0% | 57.5% | 50.2% |
| Never Married | 23.3% | 27.8% | 33.8% |
| Divorced | 12.5% | 16.6% | 10.8% |
| Widowed | 6.2% | 13.1% | 5.6% |
| space5 | | | |
| Household Size | 2.28 | 2.45 | 2.60 |
| Households | 1,183 | 1,328 | 124,010,992 |
| Family Households | 796 | 793 | 80,755,759 |
| Married couple, w/children | 22.9% | 30.9% | 30.5% |
| Married couple, no children | 59.3% | 38.5% | 42.9% |
| Non Family Households | 387 | 535 | 43,255,233 |
| Single householder, w/children | 11.1% | 23.7% | 15.8% |
| Single householder, no children | 6.8% | 6.9% | 10.8% |