| | Eureka, IL | Machesney Park, IL | United States |
| Population | 5,569 | 22,870 | 329,725,481 |
| Female Population | 53.8% | 52.2% | 50.5% |
| Male Population | 46.2% | 47.8% | 49.5% |
| Median Age | 38.1 | 39.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 5,345 | 23,496 | 309,327,143 |
| Population - 2000 | 4,871 | 20,759 | 285,036,114 |
| Population - 1990 | 4,435 | 19,033 | 251,960,433 |
| Pop. 2000 to Now | 7.4% | 9.2% | 15.6% |
| Pop. 1990 to Now | 18.0% | 19.2% | 30.8% |
| space4 | | | |
| Population Density | 2,096.8 | 1,802.9 | 93.4 |
| Land Area | 2.7 | 12.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Eureka, IL | Machesney Park, IL | United States |
| Age 0 to 4 | 6.2% | 5.0% | 5.9% |
| Age 5 to 9 | 4.8% | 6.8% | 6.1% |
| Age 10 to 14 | 5.6% | 7.0% | 6.6% |
| Age 15 to 17 | 1.7% | 4.0% | 3.9% |
| Age 18 to 20 | 7.1% | 4.2% | 4.0% |
| Age 21 to 24 | 10.6% | 4.9% | 5.2% |
| Age 25 to 34 | 10.9% | 11.4% | 13.8% |
| Age 35 to 44 | 10.6% | 13.3% | 12.9% |
| Age 45 to 54 | 10.2% | 15.4% | 12.6% |
| Age 55 to 59 | 7.1% | 6.3% | 6.7% |
| Age 60 to 64 | 6.4% | 5.6% | 6.3% |
| Age 65 to 74 | 5.9% | 11.6% | 9.6% |
| Age 75 to 84 | 6.8% | 3.7% | 4.5% |
| Age 85 and over | 6.1% | 1.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Eureka, IL | Machesney Park, IL | United States |
| White | 90.9% | 84.6% | 59.4% |
| Black | 1.5% | 3.3% | 12.2% |
| Asian | 0.1% | 1.6% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 2.5% | 3.3% | 3.2% |
| Hispanic | 5.0% | 7.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Eureka, IL | Machesney Park, IL | United States |
| Married Population | 56.2% | 52.4% | 49.8% |
| Currently Married | 55.7% | 51.4% | 48.0% |
| Married but Separated | 0.5% | 1.0% | 1.8% |
| Single Population | 43.8% | 47.6% | 50.2% |
| Never Married | 22.3% | 30.5% | 33.8% |
| Divorced | 11.8% | 11.6% | 10.8% |
| Widowed | 9.7% | 5.5% | 5.6% |
| space5 | | | |
| Household Size | 2.24 | 2.64 | 2.60 |
| Households | 2,211 | 8,658 | 124,010,992 |
| Family Households | 1,448 | 6,172 | 80,755,759 |
| Married couple, w/children | 40.9% | 26.7% | 30.5% |
| Married couple, no children | 47.9% | 46.1% | 42.9% |
| Non Family Households | 763 | 2,486 | 43,255,233 |
| Single householder, w/children | 6.1% | 15.8% | 15.8% |
| Single householder, no children | 5.1% | 11.4% | 10.8% |