| | The Plains, VA | Haymarket, VA | United States |
| Population | 273 | 1,556 | 329,725,481 |
| Female Population | 57.1% | 42.8% | 50.5% |
| Male Population | 42.9% | 57.2% | 49.5% |
| Median Age | 38.7 | 36.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 219 | 1,480 | 309,327,143 |
| Population - 2000 | 266 | 879 | 285,036,114 |
| Population - 1990 | 219 | 483 | 251,960,433 |
| Pop. 2000 to Now | -10.9% | 91.9% | 15.6% |
| Pop. 1990 to Now | 8.2% | 249.3% | 30.8% |
| space4 | | | |
| Population Density | 989.1 | 2,710.8 | 93.4 |
| Land Area | 0.3 | 0.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | The Plains, VA | Haymarket, VA | United States |
| Age 0 to 4 | 11.7% | 6.4% | 5.9% |
| Age 5 to 9 | 4.8% | 5.0% | 6.1% |
| Age 10 to 14 | 2.6% | 10.5% | 6.6% |
| Age 15 to 17 | 6.6% | 4.0% | 3.9% |
| Age 18 to 20 | 4.8% | 8.7% | 4.0% |
| Age 21 to 24 | 9.5% | 4.0% | 5.2% |
| Age 25 to 34 | 6.2% | 9.5% | 13.8% |
| Age 35 to 44 | 8.4% | 17.7% | 12.9% |
| Age 45 to 54 | 25.3% | 12.8% | 12.6% |
| Age 55 to 59 | 2.2% | 6.6% | 6.7% |
| Age 60 to 64 | 7.7% | 3.1% | 6.3% |
| Age 65 to 74 | 6.2% | 7.4% | 9.6% |
| Age 75 to 84 | 2.2% | 4.0% | 4.5% |
| Age 85 and over | 1.8% | 0.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | The Plains, VA | Haymarket, VA | United States |
| White | 54.9% | 62.3% | 59.4% |
| Black | 0.0% | 14.8% | 12.2% |
| Asian | 0.4% | 12.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 11.0% | 2.4% | 3.2% |
| Hispanic | 33.7% | 7.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | The Plains, VA | Haymarket, VA | United States |
| Married Population | 33.5% | 60.0% | 49.8% |
| Currently Married | 33.5% | 59.3% | 48.0% |
| Married but Separated | 0.0% | 0.7% | 1.8% |
| Single Population | 66.5% | 40.0% | 50.2% |
| Never Married | 50.7% | 31.3% | 33.8% |
| Divorced | 12.7% | 6.7% | 10.8% |
| Widowed | 3.2% | 2.1% | 5.6% |
| space5 | | | |
| Household Size | 2.90 | 3.02 | 2.60 |
| Households | 94 | 514 | 124,010,992 |
| Family Households | 54 | 402 | 80,755,759 |
| Married couple, w/children | 35.2% | 44.3% | 30.5% |
| Married couple, no children | 22.2% | 40.1% | 42.9% |
| Non Family Households | 40 | 112 | 43,255,233 |
| Single householder, w/children | 40.7% | 9.5% | 15.8% |
| Single householder, no children | 1.9% | 6.2% | 10.8% |