| | Parkston, SD | Fairfield, IA | United States |
| Population | 1,761 | 9,653 | 329,725,481 |
| Female Population | 47.3% | 49.5% | 50.5% |
| Male Population | 52.7% | 50.5% | 49.5% |
| Median Age | 37.1 | 39.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,514 | 9,479 | 309,327,143 |
| Population - 2000 | 1,674 | 9,509 | 285,036,114 |
| Population - 1990 | 1,572 | 9,768 | 251,960,433 |
| Pop. 2000 to Now | -13.0% | 10.4% | 15.6% |
| Pop. 1990 to Now | -7.4% | 7.5% | 30.8% |
| space4 | | | |
| Population Density | 1,351.5 | 1,475.3 | 93.4 |
| Land Area | 1.3 | 6.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Parkston, SD | Fairfield, IA | United States |
| Age 0 to 4 | 9.4% | 5.1% | 5.9% |
| Age 5 to 9 | 8.1% | 7.2% | 6.1% |
| Age 10 to 14 | 8.9% | 5.0% | 6.6% |
| Age 15 to 17 | 4.8% | 4.0% | 3.9% |
| Age 18 to 20 | 1.4% | 2.3% | 4.0% |
| Age 21 to 24 | 3.4% | 5.9% | 5.2% |
| Age 25 to 34 | 11.0% | 16.8% | 13.8% |
| Age 35 to 44 | 14.0% | 10.5% | 12.9% |
| Age 45 to 54 | 7.3% | 10.5% | 12.6% |
| Age 55 to 59 | 5.2% | 5.0% | 6.7% |
| Age 60 to 64 | 7.3% | 5.0% | 6.3% |
| Age 65 to 74 | 11.6% | 14.8% | 9.6% |
| Age 75 to 84 | 3.7% | 5.0% | 4.5% |
| Age 85 and over | 4.1% | 3.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Parkston, SD | Fairfield, IA | United States |
| White | 92.9% | 72.6% | 59.4% |
| Black | 0.0% | 10.4% | 12.2% |
| Asian | 0.0% | 8.5% | 5.6% |
| Native American | 0.5% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.4% | 0.4% |
| Two or More Races | 2.8% | 3.8% | 3.2% |
| Hispanic | 3.8% | 4.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Parkston, SD | Fairfield, IA | United States |
| Married Population | 55.5% | 39.5% | 49.8% |
| Currently Married | 55.5% | 38.4% | 48.0% |
| Married but Separated | 0.0% | 1.2% | 1.8% |
| Single Population | 44.5% | 60.5% | 50.2% |
| Never Married | 21.0% | 36.1% | 33.8% |
| Divorced | 18.0% | 19.6% | 10.8% |
| Widowed | 5.5% | 4.7% | 5.6% |
| space5 | | | |
| Household Size | 2.35 | 2.21 | 2.60 |
| Households | 729 | 4,045 | 124,010,992 |
| Family Households | 462 | 2,081 | 80,755,759 |
| Married couple, w/children | 30.1% | 25.3% | 30.5% |
| Married couple, no children | 48.3% | 46.0% | 42.9% |
| Non Family Households | 267 | 1,964 | 43,255,233 |
| Single householder, w/children | 15.4% | 20.7% | 15.8% |
| Single householder, no children | 6.3% | 8.0% | 10.8% |