| | Isabel, SD | Eagle Butte, SD | United States |
| Population | 186 | 1,421 | 329,725,481 |
| Female Population | 53.2% | 49.8% | 50.5% |
| Male Population | 46.8% | 50.2% | 49.5% |
| Median Age | 38.1 | 29.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 136 | 1,428 | 309,327,143 |
| Population - 2000 | 239 | 619 | 285,036,114 |
| Population - 1990 | 319 | 489 | 251,960,433 |
| Pop. 2000 to Now | -37.2% | 129.1% | 15.6% |
| Pop. 1990 to Now | -53.0% | 190.0% | 30.8% |
| space4 | | | |
| Population Density | 205.5 | 1,212.5 | 93.4 |
| Land Area | 0.9 | 1.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Isabel, SD | Eagle Butte, SD | United States |
| Age 0 to 4 | 1.1% | 8.3% | 5.9% |
| Age 5 to 9 | 5.4% | 9.1% | 6.1% |
| Age 10 to 14 | 10.8% | 10.3% | 6.6% |
| Age 15 to 17 | 4.8% | 7.0% | 3.9% |
| Age 18 to 20 | 0.5% | 3.7% | 4.0% |
| Age 21 to 24 | 7.5% | 4.7% | 5.2% |
| Age 25 to 34 | 7.0% | 13.4% | 13.8% |
| Age 35 to 44 | 21.0% | 20.5% | 12.9% |
| Age 45 to 54 | 8.1% | 6.5% | 12.6% |
| Age 55 to 59 | 10.8% | 4.8% | 6.7% |
| Age 60 to 64 | 9.1% | 5.9% | 6.3% |
| Age 65 to 74 | 9.1% | 2.2% | 9.6% |
| Age 75 to 84 | 2.7% | 3.0% | 4.5% |
| Age 85 and over | 2.2% | 0.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Isabel, SD | Eagle Butte, SD | United States |
| White | 71.0% | 7.7% | 59.4% |
| Black | 1.1% | 0.3% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 26.9% | 78.6% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.1% | 1.7% | 3.2% |
| Hispanic | 0.0% | 11.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Isabel, SD | Eagle Butte, SD | United States |
| Married Population | 39.6% | 22.7% | 49.8% |
| Currently Married | 39.6% | 21.7% | 48.0% |
| Married but Separated | 0.0% | 1.0% | 1.8% |
| Single Population | 60.4% | 77.3% | 50.2% |
| Never Married | 37.0% | 57.0% | 33.8% |
| Divorced | 18.2% | 16.3% | 10.8% |
| Widowed | 5.2% | 4.0% | 5.6% |
| space5 | | | |
| Household Size | 2.07 | 3.60 | 2.60 |
| Households | 90 | 387 | 124,010,992 |
| Family Households | 55 | 289 | 80,755,759 |
| Married couple, w/children | 20.0% | 14.9% | 30.5% |
| Married couple, no children | 43.6% | 17.3% | 42.9% |
| Non Family Households | 35 | 98 | 43,255,233 |
| Single householder, w/children | 23.6% | 54.0% | 15.8% |
| Single householder, no children | 12.7% | 13.8% | 10.8% |