| | River Hills, WI | Lake Forest, IL | United States |
| Population | 1,496 | 19,450 | 329,725,481 |
| Female Population | 51.1% | 51.5% | 50.5% |
| Male Population | 48.9% | 48.5% | 49.5% |
| Median Age | 52 | 46.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,601 | 19,392 | 309,327,143 |
| Population - 2000 | 1,631 | 20,059 | 285,036,114 |
| Population - 1990 | 1,612 | 17,836 | 251,960,433 |
| Pop. 2000 to Now | -3.4% | -3.4% | 15.6% |
| Pop. 1990 to Now | -2.3% | 8.7% | 30.8% |
| space4 | | | |
| Population Density | 290.2 | 1,130.8 | 93.4 |
| Land Area | 5.2 | 17.2 | 3,531,905.4 |
| Water Area | 0.2 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | River Hills, WI | Lake Forest, IL | United States |
| Age 0 to 4 | 4.3% | 3.8% | 5.9% |
| Age 5 to 9 | 3.3% | 4.7% | 6.1% |
| Age 10 to 14 | 8.2% | 6.9% | 6.6% |
| Age 15 to 17 | 7.0% | 4.8% | 3.9% |
| Age 18 to 20 | 1.7% | 6.2% | 4.0% |
| Age 21 to 24 | 4.5% | 6.7% | 5.2% |
| Age 25 to 34 | 3.2% | 7.8% | 13.8% |
| Age 35 to 44 | 8.4% | 7.7% | 12.9% |
| Age 45 to 54 | 16.6% | 13.4% | 12.6% |
| Age 55 to 59 | 9.8% | 7.5% | 6.7% |
| Age 60 to 64 | 6.6% | 6.1% | 6.3% |
| Age 65 to 74 | 14.0% | 13.2% | 9.6% |
| Age 75 to 84 | 9.1% | 7.3% | 4.5% |
| Age 85 and over | 3.4% | 4.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | River Hills, WI | Lake Forest, IL | United States |
| White | 76.1% | 82.1% | 59.4% |
| Black | 7.9% | 1.0% | 12.2% |
| Asian | 8.4% | 7.2% | 5.6% |
| Native American | 0.1% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.9% | 0.8% | 0.4% |
| Two or More Races | 5.1% | 3.6% | 3.2% |
| Hispanic | 1.5% | 5.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | River Hills, WI | Lake Forest, IL | United States |
| Married Population | 71.0% | 57.1% | 49.8% |
| Currently Married | 70.6% | 56.6% | 48.0% |
| Married but Separated | 0.4% | 0.5% | 1.8% |
| Single Population | 29.0% | 42.9% | 50.2% |
| Never Married | 21.2% | 30.5% | 33.8% |
| Divorced | 4.3% | 6.3% | 10.8% |
| Widowed | 3.5% | 6.1% | 5.6% |
| space5 | | | |
| Household Size | 2.89 | 2.61 | 2.60 |
| Households | 517 | 7,014 | 124,010,992 |
| Family Households | 435 | 5,085 | 80,755,759 |
| Married couple, w/children | 37.5% | 34.9% | 30.5% |
| Married couple, no children | 57.2% | 54.1% | 42.9% |
| Non Family Households | 82 | 1,929 | 43,255,233 |
| Single householder, w/children | 1.4% | 4.8% | 15.8% |
| Single householder, no children | 3.9% | 6.2% | 10.8% |