| | Hardin, MT | Mahomet, IL | United States |
| Population | 3,754 | 9,297 | 329,725,481 |
| Female Population | 49.4% | 52.0% | 50.5% |
| Male Population | 50.6% | 48.1% | 49.5% |
| Median Age | 32.4 | 37.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,673 | 7,330 | 309,327,143 |
| Population - 2000 | 3,384 | 4,877 | 285,036,114 |
| Population - 1990 | 2,940 | 3,103 | 251,960,433 |
| Pop. 2000 to Now | 9.5% | 83.9% | 15.6% |
| Pop. 1990 to Now | 26.0% | 189.0% | 30.8% |
| space4 | | | |
| Population Density | 1,264.8 | 974.5 | 93.4 |
| Land Area | 3.0 | 9.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Hardin, MT | Mahomet, IL | United States |
| Age 0 to 4 | 8.1% | 7.3% | 5.9% |
| Age 5 to 9 | 12.8% | 9.3% | 6.1% |
| Age 10 to 14 | 6.8% | 11.0% | 6.6% |
| Age 15 to 17 | 6.0% | 3.5% | 3.9% |
| Age 18 to 20 | 7.3% | 5.4% | 4.0% |
| Age 21 to 24 | 3.0% | 2.5% | 5.2% |
| Age 25 to 34 | 12.8% | 8.1% | 13.8% |
| Age 35 to 44 | 11.7% | 17.3% | 12.9% |
| Age 45 to 54 | 10.0% | 13.8% | 12.6% |
| Age 55 to 59 | 5.0% | 7.2% | 6.7% |
| Age 60 to 64 | 5.2% | 6.3% | 6.3% |
| Age 65 to 74 | 7.6% | 5.8% | 9.6% |
| Age 75 to 84 | 2.8% | 1.9% | 4.5% |
| Age 85 and over | 0.7% | 0.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Hardin, MT | Mahomet, IL | United States |
| White | 36.9% | 90.3% | 59.4% |
| Black | 0.0% | 0.5% | 12.2% |
| Asian | 0.4% | 1.3% | 5.6% |
| Native American | 44.3% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.4% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 3.9% | 4.6% | 3.2% |
| Hispanic | 14.5% | 2.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Hardin, MT | Mahomet, IL | United States |
| Married Population | 42.8% | 72.3% | 49.8% |
| Currently Married | 40.8% | 72.3% | 48.0% |
| Married but Separated | 2.0% | 0.0% | 1.8% |
| Single Population | 57.2% | 27.7% | 50.2% |
| Never Married | 40.5% | 18.5% | 33.8% |
| Divorced | 11.8% | 6.2% | 10.8% |
| Widowed | 4.9% | 3.1% | 5.6% |
| space5 | | | |
| Household Size | 3.11 | 2.96 | 2.60 |
| Households | 1,174 | 3,139 | 124,010,992 |
| Family Households | 741 | 2,623 | 80,755,759 |
| Married couple, w/children | 29.3% | 45.6% | 30.5% |
| Married couple, no children | 41.2% | 45.0% | 42.9% |
| Non Family Households | 433 | 516 | 43,255,233 |
| Single householder, w/children | 19.7% | 5.5% | 15.8% |
| Single householder, no children | 9.9% | 3.9% | 10.8% |