| | Manhattan, NY | Fairfax, VA | United States |
| Population | 1,669,127 | 23,980 | 329,725,481 |
| Female Population | 52.4% | 51.2% | 50.5% |
| Male Population | 47.6% | 48.9% | 49.5% |
| Median Age | 38.1 | 37.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,589,041 | 22,616 | 309,327,143 |
| Population - 2000 | 1,537,195 | 21,498 | 285,036,114 |
| Population - 1990 | 1,487,536 | 19,622 | 251,960,433 |
| Pop. 2000 to Now | 4.9% | 9.0% | 15.6% |
| Pop. 1990 to Now | 8.4% | 19.4% | 30.8% |
| space4 | | | |
| Population Density | 73,114.3 | 3,843.0 | 93.4 |
| Land Area | 22.8 | 6.2 | 3,531,905.4 |
| Water Area | 10.8 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Manhattan, NY | Fairfax, VA | United States |
| Age 0 to 4 | 4.6% | 7.4% | 5.9% |
| Age 5 to 9 | 3.8% | 5.5% | 6.1% |
| Age 10 to 14 | 3.9% | 6.0% | 6.6% |
| Age 15 to 17 | 2.1% | 3.5% | 3.9% |
| Age 18 to 20 | 3.2% | 3.4% | 4.0% |
| Age 21 to 24 | 5.6% | 6.0% | 5.2% |
| Age 25 to 34 | 21.5% | 13.1% | 13.8% |
| Age 35 to 44 | 14.6% | 13.8% | 12.9% |
| Age 45 to 54 | 12.3% | 13.2% | 12.6% |
| Age 55 to 59 | 6.0% | 7.9% | 6.7% |
| Age 60 to 64 | 5.5% | 5.4% | 6.3% |
| Age 65 to 74 | 9.3% | 8.6% | 9.6% |
| Age 75 to 84 | 5.1% | 4.2% | 4.5% |
| Age 85 and over | 2.4% | 2.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Manhattan, NY | Fairfax, VA | United States |
| White | 46.7% | 54.6% | 59.4% |
| Black | 12.1% | 5.4% | 12.2% |
| Asian | 11.8% | 18.4% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.6% | 0.3% | 0.4% |
| Two or More Races | 2.9% | 3.7% | 3.2% |
| Hispanic | 25.6% | 17.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Manhattan, NY | Fairfax, VA | United States |
| Married Population | 37.1% | 56.3% | 49.8% |
| Currently Married | 34.7% | 55.1% | 48.0% |
| Married but Separated | 2.4% | 1.2% | 1.8% |
| Single Population | 62.9% | 43.7% | 50.2% |
| Never Married | 49.6% | 31.9% | 33.8% |
| Divorced | 8.7% | 7.3% | 10.8% |
| Widowed | 4.6% | 4.5% | 5.6% |
| space5 | | | |
| Household Size | 2.09 | 2.58 | 2.60 |
| Households | 767,213 | 9,090 | 124,010,992 |
| Family Households | 327,372 | 5,849 | 80,755,759 |
| Married couple, w/children | 25.3% | 41.2% | 30.5% |
| Married couple, no children | 41.4% | 42.7% | 42.9% |
| Non Family Households | 439,841 | 3,241 | 43,255,233 |
| Single householder, w/children | 16.3% | 6.1% | 15.8% |
| Single householder, no children | 17.0% | 10.0% | 10.8% |