| | McNair, VA | Belmont, VA | United States |
| Population | 20,980 | 9,589 | 329,725,481 |
| Female Population | 47.1% | 48.8% | 50.5% |
| Male Population | 52.9% | 51.2% | 49.5% |
| Median Age | 31.1 | 37.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 15,213 | 5,267 | 309,327,143 |
| Population - 2000 | 7,528 | 468 | 285,036,114 |
| Population - 1990 | 719 | 24 | 251,960,433 |
| Pop. 2000 to Now | 183.8% | 1,484.6% | 15.6% |
| Pop. 1990 to Now | 2,871.5% | 30,800.0% | 30.8% |
| space4 | | | |
| Population Density | 10,274.2 | 4,691.3 | 93.4 |
| Land Area | 2.0 | 2.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | McNair, VA | Belmont, VA | United States |
| Age 0 to 4 | 7.6% | 6.9% | 5.9% |
| Age 5 to 9 | 7.5% | 8.2% | 6.1% |
| Age 10 to 14 | 5.3% | 10.4% | 6.6% |
| Age 15 to 17 | 2.8% | 5.1% | 3.9% |
| Age 18 to 20 | 1.8% | 4.5% | 4.0% |
| Age 21 to 24 | 7.3% | 3.1% | 5.2% |
| Age 25 to 34 | 27.6% | 10.1% | 13.8% |
| Age 35 to 44 | 19.5% | 14.2% | 12.9% |
| Age 45 to 54 | 11.7% | 23.4% | 12.6% |
| Age 55 to 59 | 2.7% | 5.7% | 6.7% |
| Age 60 to 64 | 2.7% | 2.4% | 6.3% |
| Age 65 to 74 | 1.7% | 2.8% | 9.6% |
| Age 75 to 84 | 1.1% | 2.7% | 4.5% |
| Age 85 and over | 0.6% | 0.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | McNair, VA | Belmont, VA | United States |
| White | 30.9% | 56.7% | 59.4% |
| Black | 10.9% | 1.7% | 12.2% |
| Asian | 42.5% | 25.8% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.6% | 0.0% | 0.2% |
| Other | 0.2% | 0.6% | 0.4% |
| Two or More Races | 4.1% | 5.0% | 3.2% |
| Hispanic | 10.8% | 9.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | McNair, VA | Belmont, VA | United States |
| Married Population | 54.3% | 69.0% | 49.8% |
| Currently Married | 51.9% | 67.8% | 48.0% |
| Married but Separated | 2.4% | 1.1% | 1.8% |
| Single Population | 45.7% | 31.0% | 50.2% |
| Never Married | 36.9% | 25.3% | 33.8% |
| Divorced | 7.2% | 4.8% | 10.8% |
| Widowed | 1.6% | 0.9% | 5.6% |
| space5 | | | |
| Household Size | 2.52 | 3.19 | 2.60 |
| Households | 8,318 | 3,003 | 124,010,992 |
| Family Households | 4,572 | 2,539 | 80,755,759 |
| Married couple, w/children | 53.9% | 61.0% | 30.5% |
| Married couple, no children | 31.1% | 28.8% | 42.9% |
| Non Family Households | 3,746 | 464 | 43,255,233 |
| Single householder, w/children | 8.0% | 8.2% | 15.8% |
| Single householder, no children | 6.9% | 1.9% | 10.8% |