| | Mackay, ID | Challis, ID | United States |
| Population | 603 | 891 | 329,725,481 |
| Female Population | 49.3% | 50.7% | 50.5% |
| Male Population | 50.8% | 49.3% | 49.5% |
| Median Age | 43.4 | 43.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 511 | 1,093 | 309,327,143 |
| Population - 2000 | 566 | 909 | 285,036,114 |
| Population - 1990 | 574 | 1,073 | 251,960,433 |
| Pop. 2000 to Now | -12.9% | 17.3% | 15.6% |
| Pop. 1990 to Now | -14.1% | -0.7% | 30.8% |
| space4 | | | |
| Population Density | 696.3 | 464.3 | 93.4 |
| Land Area | 0.9 | 1.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Mackay, ID | Challis, ID | United States |
| Age 0 to 4 | 10.3% | 4.8% | 5.9% |
| Age 5 to 9 | 9.1% | 10.7% | 6.1% |
| Age 10 to 14 | 0.0% | 8.1% | 6.6% |
| Age 15 to 17 | 3.6% | 2.2% | 3.9% |
| Age 18 to 20 | 8.8% | 0.7% | 4.0% |
| Age 21 to 24 | 5.6% | 5.8% | 5.2% |
| Age 25 to 34 | 2.2% | 8.6% | 13.8% |
| Age 35 to 44 | 18.6% | 12.7% | 12.9% |
| Age 45 to 54 | 5.3% | 17.8% | 12.6% |
| Age 55 to 59 | 1.7% | 8.1% | 6.7% |
| Age 60 to 64 | 10.9% | 6.3% | 6.3% |
| Age 65 to 74 | 15.6% | 11.9% | 9.6% |
| Age 75 to 84 | 6.6% | 1.7% | 4.5% |
| Age 85 and over | 1.7% | 0.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Mackay, ID | Challis, ID | United States |
| White | 79.6% | 82.6% | 59.4% |
| Black | 0.0% | 0.0% | 12.2% |
| Asian | 0.0% | 0.1% | 5.6% |
| Native American | 0.0% | 2.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 3.0% | 0.4% |
| Two or More Races | 6.3% | 1.2% | 3.2% |
| Hispanic | 14.1% | 10.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Mackay, ID | Challis, ID | United States |
| Married Population | 41.6% | 49.3% | 49.8% |
| Currently Married | 41.6% | 46.4% | 48.0% |
| Married but Separated | 0.0% | 2.9% | 1.8% |
| Single Population | 58.4% | 50.7% | 50.2% |
| Never Married | 31.5% | 24.5% | 33.8% |
| Divorced | 20.8% | 25.4% | 10.8% |
| Widowed | 6.2% | 0.7% | 5.6% |
| space5 | | | |
| Household Size | 3.30 | 2.48 | 2.60 |
| Households | 183 | 346 | 124,010,992 |
| Family Households | 103 | 150 | 80,755,759 |
| Married couple, w/children | 26.2% | 38.7% | 30.5% |
| Married couple, no children | 61.2% | 36.0% | 42.9% |
| Non Family Households | 80 | 196 | 43,255,233 |
| Single householder, w/children | 0.0% | 12.0% | 15.8% |
| Single householder, no children | 12.6% | 13.3% | 10.8% |