| | Round Hill, VA | Las Vegas, NV | United States |
| Population | 698 | 634,786 | 329,725,481 |
| Female Population | 49.3% | 49.8% | 50.5% |
| Male Population | 50.7% | 50.2% | 49.5% |
| Median Age | 41.5 | 37.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 538 | 584,600 | 309,327,143 |
| Population - 2000 | 500 | 478,434 | 285,036,114 |
| Population - 1990 | 514 | 258,295 | 251,960,433 |
| Pop. 2000 to Now | 31.4% | 38.5% | 15.6% |
| Pop. 1990 to Now | 27.8% | 156.4% | 30.8% |
| space4 | | | |
| Population Density | 1,901.9 | 4,477.6 | 93.4 |
| Land Area | 0.4 | 141.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Round Hill, VA | Las Vegas, NV | United States |
| Age 0 to 4 | 4.6% | 6.0% | 5.9% |
| Age 5 to 9 | 4.6% | 6.4% | 6.1% |
| Age 10 to 14 | 5.9% | 7.0% | 6.6% |
| Age 15 to 17 | 5.2% | 4.1% | 3.9% |
| Age 18 to 20 | 4.9% | 3.5% | 4.0% |
| Age 21 to 24 | 3.2% | 4.7% | 5.2% |
| Age 25 to 34 | 9.6% | 14.4% | 13.8% |
| Age 35 to 44 | 22.4% | 13.7% | 12.9% |
| Age 45 to 54 | 18.5% | 13.2% | 12.6% |
| Age 55 to 59 | 6.0% | 6.5% | 6.7% |
| Age 60 to 64 | 2.0% | 5.7% | 6.3% |
| Age 65 to 74 | 7.2% | 9.1% | 9.6% |
| Age 75 to 84 | 5.3% | 4.2% | 4.5% |
| Age 85 and over | 0.9% | 1.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Round Hill, VA | Las Vegas, NV | United States |
| White | 89.1% | 42.1% | 59.4% |
| Black | 1.9% | 11.1% | 12.2% |
| Asian | 0.3% | 6.6% | 5.6% |
| Native American | 0.0% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.7% | 0.2% |
| Other | 0.0% | 0.6% | 0.4% |
| Two or More Races | 1.0% | 4.5% | 3.2% |
| Hispanic | 7.7% | 34.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Round Hill, VA | Las Vegas, NV | United States |
| Married Population | 54.6% | 45.7% | 49.8% |
| Currently Married | 53.5% | 43.7% | 48.0% |
| Married but Separated | 1.2% | 2.0% | 1.8% |
| Single Population | 45.4% | 54.3% | 50.2% |
| Never Married | 36.3% | 35.6% | 33.8% |
| Divorced | 4.7% | 13.5% | 10.8% |
| Widowed | 4.4% | 5.2% | 5.6% |
| space5 | | | |
| Household Size | 2.24 | 2.65 | 2.60 |
| Households | 311 | 236,410 | 124,010,992 |
| Family Households | 182 | 147,681 | 80,755,759 |
| Married couple, w/children | 31.9% | 28.8% | 30.5% |
| Married couple, no children | 53.3% | 38.3% | 42.9% |
| Non Family Households | 129 | 88,729 | 43,255,233 |
| Single householder, w/children | 9.9% | 19.5% | 15.8% |
| Single householder, no children | 4.9% | 13.5% | 10.8% |