| | Harrington, DE | Polson, MT | United States |
| Population | 3,730 | 5,161 | 329,725,481 |
| Female Population | 54.2% | 50.6% | 50.5% |
| Male Population | 45.8% | 49.4% | 49.5% |
| Median Age | 28.5 | 46.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,572 | 4,606 | 309,327,143 |
| Population - 2000 | 3,174 | 4,041 | 285,036,114 |
| Population - 1990 | 2,311 | 3,283 | 251,960,433 |
| Pop. 2000 to Now | 15.4% | 28.2% | 15.6% |
| Pop. 1990 to Now | 58.5% | 57.8% | 30.8% |
| space4 | | | |
| Population Density | 1,369.8 | 1,137.8 | 93.4 |
| Land Area | 2.7 | 4.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Harrington, DE | Polson, MT | United States |
| Age 0 to 4 | 15.4% | 6.1% | 5.9% |
| Age 5 to 9 | 16.0% | 4.6% | 6.1% |
| Age 10 to 14 | 5.2% | 6.6% | 6.6% |
| Age 15 to 17 | 0.8% | 2.9% | 3.9% |
| Age 18 to 20 | 1.1% | 3.9% | 4.0% |
| Age 21 to 24 | 5.1% | 6.6% | 5.2% |
| Age 25 to 34 | 21.0% | 9.5% | 13.8% |
| Age 35 to 44 | 7.7% | 8.1% | 12.9% |
| Age 45 to 54 | 8.5% | 13.1% | 12.6% |
| Age 55 to 59 | 3.0% | 8.8% | 6.7% |
| Age 60 to 64 | 4.3% | 7.5% | 6.3% |
| Age 65 to 74 | 5.5% | 12.4% | 9.6% |
| Age 75 to 84 | 4.3% | 8.5% | 4.5% |
| Age 85 and over | 2.1% | 1.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Harrington, DE | Polson, MT | United States |
| White | 56.4% | 68.4% | 59.4% |
| Black | 29.4% | 0.9% | 12.2% |
| Asian | 1.7% | 1.0% | 5.6% |
| Native American | 0.0% | 13.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.5% | 0.0% | 0.4% |
| Two or More Races | 3.3% | 9.8% | 3.2% |
| Hispanic | 8.7% | 6.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Harrington, DE | Polson, MT | United States |
| Married Population | 47.7% | 46.7% | 49.8% |
| Currently Married | 47.0% | 46.0% | 48.0% |
| Married but Separated | 0.7% | 0.7% | 1.8% |
| Single Population | 52.3% | 53.3% | 50.2% |
| Never Married | 33.2% | 27.2% | 33.8% |
| Divorced | 11.4% | 20.8% | 10.8% |
| Widowed | 7.7% | 5.2% | 5.6% |
| space5 | | | |
| Household Size | 2.79 | 2.35 | 2.60 |
| Households | 1,338 | 2,157 | 124,010,992 |
| Family Households | 944 | 1,310 | 80,755,759 |
| Married couple, w/children | 37.4% | 18.6% | 30.5% |
| Married couple, no children | 21.1% | 47.5% | 42.9% |
| Non Family Households | 394 | 847 | 43,255,233 |
| Single householder, w/children | 21.8% | 16.9% | 15.8% |
| Single householder, no children | 19.7% | 17.0% | 10.8% |