| | Waubay, SD | Milbank, SD | United States |
| Population | 403 | 3,488 | 329,725,481 |
| Female Population | 50.4% | 51.8% | 50.5% |
| Male Population | 49.6% | 48.2% | 49.5% |
| Median Age | 56.9 | 41.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 577 | 3,349 | 309,327,143 |
| Population - 2000 | 662 | 3,640 | 285,036,114 |
| Population - 1990 | 647 | 3,879 | 251,960,433 |
| Pop. 2000 to Now | -16.9% | -15.8% | 15.6% |
| Pop. 1990 to Now | -15.0% | -21.0% | 30.8% |
| space4 | | | |
| Population Density | 277.2 | 1,235.6 | 93.4 |
| Land Area | 1.5 | 2.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Waubay, SD | Milbank, SD | United States |
| Age 0 to 4 | 3.2% | 4.4% | 5.9% |
| Age 5 to 9 | 3.2% | 8.3% | 6.1% |
| Age 10 to 14 | 8.2% | 5.9% | 6.6% |
| Age 15 to 17 | 6.7% | 2.4% | 3.9% |
| Age 18 to 20 | 2.7% | 3.4% | 4.0% |
| Age 21 to 24 | 0.0% | 4.2% | 5.2% |
| Age 25 to 34 | 5.0% | 14.1% | 13.8% |
| Age 35 to 44 | 10.9% | 12.8% | 12.9% |
| Age 45 to 54 | 6.5% | 8.7% | 12.6% |
| Age 55 to 59 | 4.5% | 5.2% | 6.7% |
| Age 60 to 64 | 6.7% | 8.5% | 6.3% |
| Age 65 to 74 | 25.8% | 12.9% | 9.6% |
| Age 75 to 84 | 14.4% | 6.6% | 4.5% |
| Age 85 and over | 2.2% | 2.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Waubay, SD | Milbank, SD | United States |
| White | 59.1% | 88.2% | 59.4% |
| Black | 0.0% | 0.1% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 31.3% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 9.7% | 1.5% | 3.2% |
| Hispanic | 0.0% | 10.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Waubay, SD | Milbank, SD | United States |
| Married Population | 44.2% | 63.0% | 49.8% |
| Currently Married | 43.3% | 62.9% | 48.0% |
| Married but Separated | 0.9% | 0.1% | 1.8% |
| Single Population | 55.8% | 37.0% | 50.2% |
| Never Married | 28.8% | 23.2% | 33.8% |
| Divorced | 14.0% | 10.0% | 10.8% |
| Widowed | 13.1% | 3.8% | 5.6% |
| space5 | | | |
| Household Size | 2.28 | 2.41 | 2.60 |
| Households | 177 | 1,397 | 124,010,992 |
| Family Households | 111 | 1,009 | 80,755,759 |
| Married couple, w/children | 14.4% | 30.8% | 30.5% |
| Married couple, no children | 50.5% | 53.0% | 42.9% |
| Non Family Households | 66 | 388 | 43,255,233 |
| Single householder, w/children | 14.4% | 4.0% | 15.8% |
| Single householder, no children | 20.7% | 12.2% | 10.8% |