| | Montclair, VA | Rockwall, TX | United States |
| Population | 21,961 | 46,150 | 329,725,481 |
| Female Population | 47.6% | 49.9% | 50.5% |
| Male Population | 52.4% | 50.1% | 49.5% |
| Median Age | 37.9 | 38.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 19,360 | 37,954 | 309,327,143 |
| Population - 2000 | 15,728 | 17,976 | 285,036,114 |
| Population - 1990 | 11,399 | 10,486 | 251,960,433 |
| Pop. 2000 to Now | 35.6% | 163.8% | 15.6% |
| Pop. 1990 to Now | 87.1% | 352.2% | 30.8% |
| space4 | | | |
| Population Density | 3,657.1 | 1,572.3 | 93.4 |
| Land Area | 6.0 | 29.4 | 3,531,905.4 |
| Water Area | 0.2 | 0.5 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Montclair, VA | Rockwall, TX | United States |
| Age 0 to 4 | 7.6% | 6.1% | 5.9% |
| Age 5 to 9 | 8.4% | 5.7% | 6.1% |
| Age 10 to 14 | 7.9% | 7.2% | 6.6% |
| Age 15 to 17 | 3.4% | 5.6% | 3.9% |
| Age 18 to 20 | 2.7% | 4.7% | 4.0% |
| Age 21 to 24 | 3.5% | 4.4% | 5.2% |
| Age 25 to 34 | 11.9% | 11.8% | 13.8% |
| Age 35 to 44 | 13.8% | 14.1% | 12.9% |
| Age 45 to 54 | 11.9% | 15.7% | 12.6% |
| Age 55 to 59 | 8.0% | 7.4% | 6.7% |
| Age 60 to 64 | 6.2% | 4.1% | 6.3% |
| Age 65 to 74 | 8.3% | 7.7% | 9.6% |
| Age 75 to 84 | 5.1% | 4.2% | 4.5% |
| Age 85 and over | 1.3% | 1.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Montclair, VA | Rockwall, TX | United States |
| White | 52.1% | 69.6% | 59.4% |
| Black | 21.1% | 7.5% | 12.2% |
| Asian | 7.1% | 4.0% | 5.6% |
| Native American | 0.6% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.1% | 0.2% |
| Other | 0.4% | 0.6% | 0.4% |
| Two or More Races | 6.5% | 2.4% | 3.2% |
| Hispanic | 12.1% | 15.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Montclair, VA | Rockwall, TX | United States |
| Married Population | 61.1% | 62.7% | 49.8% |
| Currently Married | 60.3% | 61.6% | 48.0% |
| Married but Separated | 0.8% | 1.1% | 1.8% |
| Single Population | 38.9% | 37.3% | 50.2% |
| Never Married | 24.9% | 25.4% | 33.8% |
| Divorced | 9.0% | 8.0% | 10.8% |
| Widowed | 5.0% | 3.9% | 5.6% |
| space5 | | | |
| Household Size | 3.10 | 2.80 | 2.60 |
| Households | 7,080 | 16,395 | 124,010,992 |
| Family Households | 5,727 | 13,267 | 80,755,759 |
| Married couple, w/children | 40.4% | 43.3% | 30.5% |
| Married couple, no children | 42.5% | 41.2% | 42.9% |
| Non Family Households | 1,353 | 3,128 | 43,255,233 |
| Single householder, w/children | 10.0% | 9.9% | 15.8% |
| Single householder, no children | 7.0% | 5.5% | 10.8% |