| | Hennepin, IL | Geneseo, IL | United States |
| Population | 832 | 6,774 | 329,725,481 |
| Female Population | 53.7% | 53.7% | 50.5% |
| Male Population | 46.3% | 46.3% | 49.5% |
| Median Age | 40.5 | 45.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 761 | 6,620 | 309,327,143 |
| Population - 2000 | 707 | 6,480 | 285,036,114 |
| Population - 1990 | 669 | 5,990 | 251,960,433 |
| Pop. 2000 to Now | -0.9% | 0.4% | 15.6% |
| Pop. 1990 to Now | 4.8% | 8.6% | 30.8% |
| space4 | | | |
| Population Density | 156.8 | 1,460.5 | 93.4 |
| Land Area | 5.3 | 4.6 | 3,531,905.4 |
| Water Area | 0.4 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Hennepin, IL | Geneseo, IL | United States |
| Age 0 to 4 | 4.7% | 1.6% | 5.9% |
| Age 5 to 9 | 7.3% | 9.2% | 6.1% |
| Age 10 to 14 | 4.1% | 7.1% | 6.6% |
| Age 15 to 17 | 6.5% | 5.4% | 3.9% |
| Age 18 to 20 | 4.1% | 2.3% | 4.0% |
| Age 21 to 24 | 5.8% | 2.3% | 5.2% |
| Age 25 to 34 | 12.0% | 10.1% | 13.8% |
| Age 35 to 44 | 9.5% | 11.2% | 12.9% |
| Age 45 to 54 | 18.9% | 13.7% | 12.6% |
| Age 55 to 59 | 6.1% | 4.2% | 6.7% |
| Age 60 to 64 | 5.8% | 6.7% | 6.3% |
| Age 65 to 74 | 8.3% | 11.4% | 9.6% |
| Age 75 to 84 | 5.2% | 7.5% | 4.5% |
| Age 85 and over | 1.8% | 7.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Hennepin, IL | Geneseo, IL | United States |
| White | 90.6% | 94.4% | 59.4% |
| Black | 0.7% | 0.0% | 12.2% |
| Asian | 0.0% | 1.6% | 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 | 1.9% | 0.8% | 3.2% |
| Hispanic | 6.7% | 3.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Hennepin, IL | Geneseo, IL | United States |
| Married Population | 50.4% | 53.8% | 49.8% |
| Currently Married | 48.0% | 53.4% | 48.0% |
| Married but Separated | 2.4% | 0.4% | 1.8% |
| Single Population | 49.6% | 46.2% | 50.2% |
| Never Married | 33.0% | 21.7% | 33.8% |
| Divorced | 13.0% | 14.6% | 10.8% |
| Widowed | 3.6% | 10.0% | 5.6% |
| space5 | | | |
| Household Size | 2.62 | 2.21 | 2.60 |
| Households | 316 | 3,028 | 124,010,992 |
| Family Households | 194 | 1,944 | 80,755,759 |
| Married couple, w/children | 34.0% | 32.7% | 30.5% |
| Married couple, no children | 52.1% | 44.3% | 42.9% |
| Non Family Households | 122 | 1,084 | 43,255,233 |
| Single householder, w/children | 10.8% | 20.6% | 15.8% |
| Single householder, no children | 3.1% | 2.4% | 10.8% |