| | Mountville, SC | Apex, NC | United States |
| Population | 66 | 58,066 | 329,725,481 |
| Female Population | 65.2% | 51.1% | 50.5% |
| Male Population | 34.9% | 49.0% | 49.5% |
| Median Age | 71.2 | 36.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 134 | 38,067 | 309,327,143 |
| Population - 2000 | 130 | 20,212 | 285,036,114 |
| Population - 1990 | 79 | 4,968 | 251,960,433 |
| Pop. 2000 to Now | -43.9% | 218.6% | 15.6% |
| Pop. 1990 to Now | -7.6% | 1,196.1% | 30.8% |
| space4 | | | |
| Population Density | 23.2 | 3,041.1 | 93.4 |
| Land Area | 2.8 | 19.1 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Mountville, SC | Apex, NC | United States |
| Age 0 to 4 | 0.0% | 6.2% | 5.9% |
| Age 5 to 9 | 7.6% | 8.2% | 6.1% |
| Age 10 to 14 | 0.0% | 9.3% | 6.6% |
| Age 15 to 17 | 0.0% | 5.2% | 3.9% |
| Age 18 to 20 | 10.6% | 3.2% | 4.0% |
| Age 21 to 24 | 0.0% | 2.9% | 5.2% |
| Age 25 to 34 | 9.1% | 12.8% | 13.8% |
| Age 35 to 44 | 13.6% | 16.7% | 12.9% |
| Age 45 to 54 | 0.0% | 16.9% | 12.6% |
| Age 55 to 59 | 0.0% | 6.3% | 6.7% |
| Age 60 to 64 | 0.0% | 3.9% | 6.3% |
| Age 65 to 74 | 45.5% | 5.4% | 9.6% |
| Age 75 to 84 | 0.0% | 1.8% | 4.5% |
| Age 85 and over | 13.6% | 1.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Mountville, SC | Apex, NC | United States |
| White | 83.3% | 72.1% | 59.4% |
| Black | 0.0% | 7.4% | 12.2% |
| Asian | 0.0% | 9.8% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.4% | 0.4% |
| Two or More Races | 0.0% | 3.7% | 3.2% |
| Hispanic | 16.7% | 6.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Mountville, SC | Apex, NC | United States |
| Married Population | 0.0% | 63.7% | 49.8% |
| Currently Married | 0.0% | 62.2% | 48.0% |
| Married but Separated | 0.0% | 1.5% | 1.8% |
| Single Population | 100.0% | 36.3% | 50.2% |
| Never Married | 26.2% | 24.8% | 33.8% |
| Divorced | 73.8% | 8.5% | 10.8% |
| Widowed | 0.0% | 3.0% | 5.6% |
| space5 | | | |
| Household Size | 1.38 | 2.83 | 2.60 |
| Households | 48 | 20,434 | 124,010,992 |
| Family Households | 9 | 15,521 | 80,755,759 |
| Married couple, w/children | 0.0% | 48.8% | 30.5% |
| Married couple, no children | 0.0% | 35.0% | 42.9% |
| Non Family Households | 39 | 4,913 | 43,255,233 |
| Single householder, w/children | 100.0% | 11.4% | 15.8% |
| Single householder, no children | 0.0% | 4.7% | 10.8% |