| | Arco, ID | Alexander, ND | United States |
| Population | 742 | 333 | 329,725,481 |
| Female Population | 60.7% | 38.4% | 50.5% |
| Male Population | 39.4% | 61.6% | 49.5% |
| Median Age | 37.3 | 34.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 990 | 224 | 309,327,143 |
| Population - 2000 | 1,026 | 217 | 285,036,114 |
| Population - 1990 | 1,016 | 216 | 251,960,433 |
| Pop. 2000 to Now | -13.0% | 62.2% | 15.6% |
| Pop. 1990 to Now | -12.1% | 63.0% | 30.8% |
| space4 | | | |
| Population Density | 694.8 | 268.1 | 93.4 |
| Land Area | 1.1 | 1.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Arco, ID | Alexander, ND | United States |
| Age 0 to 4 | 6.2% | 9.0% | 5.9% |
| Age 5 to 9 | 14.7% | 7.5% | 6.1% |
| Age 10 to 14 | 5.7% | 3.6% | 6.6% |
| Age 15 to 17 | 3.6% | 2.1% | 3.9% |
| Age 18 to 20 | 3.4% | 5.7% | 4.0% |
| Age 21 to 24 | 2.3% | 3.3% | 5.2% |
| Age 25 to 34 | 9.4% | 24.3% | 13.8% |
| Age 35 to 44 | 11.2% | 22.5% | 12.9% |
| Age 45 to 54 | 5.8% | 7.5% | 12.6% |
| Age 55 to 59 | 6.3% | 3.3% | 6.7% |
| Age 60 to 64 | 10.9% | 8.1% | 6.3% |
| Age 65 to 74 | 11.1% | 2.4% | 9.6% |
| Age 75 to 84 | 6.5% | 0.6% | 4.5% |
| Age 85 and over | 3.0% | 0.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Arco, ID | Alexander, ND | United States |
| White | 90.4% | 98.8% | 59.4% |
| Black | 0.0% | 0.0% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 7.1% | 0.0% | 3.2% |
| Hispanic | 2.4% | 1.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Arco, ID | Alexander, ND | United States |
| Married Population | 52.8% | 50.0% | 49.8% |
| Currently Married | 52.8% | 50.0% | 48.0% |
| Married but Separated | 0.0% | 0.0% | 1.8% |
| Single Population | 47.2% | 50.0% | 50.2% |
| Never Married | 14.9% | 44.0% | 33.8% |
| Divorced | 24.8% | 2.6% | 10.8% |
| Widowed | 7.5% | 3.4% | 5.6% |
| space5 | | | |
| Household Size | 2.71 | 2.71 | 2.60 |
| Households | 263 | 123 | 124,010,992 |
| Family Households | 170 | 93 | 80,755,759 |
| Married couple, w/children | 24.7% | 26.9% | 30.5% |
| Married couple, no children | 49.4% | 28.0% | 42.9% |
| Non Family Households | 93 | 30 | 43,255,233 |
| Single householder, w/children | 17.6% | 5.4% | 15.8% |
| Single householder, no children | 8.2% | 39.8% | 10.8% |