| | Summersville, MO | Gainesville, MO | United States |
| Population | 365 | 660 | 329,725,481 |
| Female Population | 52.1% | 59.6% | 50.5% |
| Male Population | 48.0% | 40.5% | 49.5% |
| Median Age | 41.2 | 49.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 502 | 823 | 309,327,143 |
| Population - 2000 | 544 | 632 | 285,036,114 |
| Population - 1990 | 571 | 659 | 251,960,433 |
| Pop. 2000 to Now | -10.5% | 22.0% | 15.6% |
| Pop. 1990 to Now | -14.7% | 17.0% | 30.8% |
| space4 | | | |
| Population Density | 329.1 | 229.9 | 93.4 |
| Land Area | 1.1 | 2.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Summersville, MO | Gainesville, MO | United States |
| Age 0 to 4 | 3.0% | 5.9% | 5.9% |
| Age 5 to 9 | 6.3% | 6.5% | 6.1% |
| Age 10 to 14 | 9.6% | 3.8% | 6.6% |
| Age 15 to 17 | 8.5% | 4.7% | 3.9% |
| Age 18 to 20 | 3.3% | 3.5% | 4.0% |
| Age 21 to 24 | 1.9% | 2.3% | 5.2% |
| Age 25 to 34 | 5.5% | 11.1% | 13.8% |
| Age 35 to 44 | 15.9% | 5.5% | 12.9% |
| Age 45 to 54 | 14.5% | 11.7% | 12.6% |
| Age 55 to 59 | 7.7% | 9.2% | 6.7% |
| Age 60 to 64 | 4.7% | 6.5% | 6.3% |
| Age 65 to 74 | 7.9% | 11.7% | 9.6% |
| Age 75 to 84 | 6.3% | 12.9% | 4.5% |
| Age 85 and over | 4.9% | 4.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Summersville, MO | Gainesville, MO | United States |
| White | 99.2% | 95.6% | 59.4% |
| Black | 0.0% | 1.2% | 12.2% |
| Asian | 0.8% | 0.0% | 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 | 0.0% | 0.6% | 3.2% |
| Hispanic | 0.0% | 2.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Summersville, MO | Gainesville, MO | United States |
| Married Population | 50.7% | 40.3% | 49.8% |
| Currently Married | 50.7% | 38.3% | 48.0% |
| Married but Separated | 0.0% | 2.0% | 1.8% |
| Single Population | 49.3% | 59.7% | 50.2% |
| Never Married | 22.6% | 23.9% | 33.8% |
| Divorced | 19.3% | 15.9% | 10.8% |
| Widowed | 7.4% | 19.9% | 5.6% |
| space5 | | | |
| Household Size | 2.30 | 2.03 | 2.60 |
| Households | 159 | 300 | 124,010,992 |
| Family Households | 72 | 157 | 80,755,759 |
| Married couple, w/children | 34.7% | 17.8% | 30.5% |
| Married couple, no children | 44.4% | 46.5% | 42.9% |
| Non Family Households | 87 | 143 | 43,255,233 |
| Single householder, w/children | 18.1% | 29.3% | 15.8% |
| Single householder, no children | 2.8% | 6.4% | 10.8% |