| | Kadoka, SD | Oregon, IL | United States |
| Population | 500 | 3,927 | 329,725,481 |
| Female Population | 51.6% | 47.6% | 50.5% |
| Male Population | 48.4% | 52.4% | 49.5% |
| Median Age | 37.8 | 45.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 659 | 3,713 | 309,327,143 |
| Population - 2000 | 706 | 4,060 | 285,036,114 |
| Population - 1990 | 736 | 3,891 | 251,960,433 |
| Pop. 2000 to Now | 0.4% | -15.1% | 15.6% |
| Pop. 1990 to Now | -3.7% | -11.4% | 30.8% |
| space4 | | | |
| Population Density | 218.8 | 2,001.5 | 93.4 |
| Land Area | 2.3 | 2.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Kadoka, SD | Oregon, IL | United States |
| Age 0 to 4 | 8.0% | 5.7% | 5.9% |
| Age 5 to 9 | 6.6% | 5.8% | 6.1% |
| Age 10 to 14 | 2.8% | 7.6% | 6.6% |
| Age 15 to 17 | 3.4% | 4.6% | 3.9% |
| Age 18 to 20 | 13.0% | 1.4% | 4.0% |
| Age 21 to 24 | 0.0% | 4.4% | 5.2% |
| Age 25 to 34 | 8.8% | 6.6% | 13.8% |
| Age 35 to 44 | 14.0% | 13.8% | 12.9% |
| Age 45 to 54 | 12.0% | 16.2% | 12.6% |
| Age 55 to 59 | 7.4% | 5.9% | 6.7% |
| Age 60 to 64 | 6.0% | 7.0% | 6.3% |
| Age 65 to 74 | 2.8% | 11.6% | 9.6% |
| Age 75 to 84 | 8.4% | 5.4% | 4.5% |
| Age 85 and over | 6.8% | 4.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Kadoka, SD | Oregon, IL | United States |
| White | 73.2% | 90.5% | 59.4% |
| Black | 0.0% | 0.8% | 12.2% |
| Asian | 1.6% | 0.4% | 5.6% |
| Native American | 22.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 3.0% | 1.0% | 3.2% |
| Hispanic | 0.2% | 7.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Kadoka, SD | Oregon, IL | United States |
| Married Population | 37.0% | 47.9% | 49.8% |
| Currently Married | 32.0% | 47.7% | 48.0% |
| Married but Separated | 5.1% | 0.3% | 1.8% |
| Single Population | 63.0% | 52.1% | 50.2% |
| Never Married | 33.2% | 28.7% | 33.8% |
| Divorced | 13.6% | 18.0% | 10.8% |
| Widowed | 16.2% | 5.4% | 5.6% |
| space5 | | | |
| Household Size | 2.38 | 2.31 | 2.60 |
| Households | 177 | 1,637 | 124,010,992 |
| Family Households | 106 | 1,004 | 80,755,759 |
| Married couple, w/children | 17.9% | 26.9% | 30.5% |
| Married couple, no children | 27.4% | 46.1% | 42.9% |
| Non Family Households | 71 | 633 | 43,255,233 |
| Single householder, w/children | 33.0% | 18.0% | 15.8% |
| Single householder, no children | 21.7% | 9.0% | 10.8% |