| | Twin Lakes, WI | Lake Forest, IL | United States |
| Population | 6,306 | 19,450 | 329,725,481 |
| Female Population | 50.7% | 51.5% | 50.5% |
| Male Population | 49.3% | 48.5% | 49.5% |
| Median Age | 47.7 | 46.4 | 38.4 |
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| Population - 2010 | 5,973 | 19,392 | 309,327,143 |
| Population - 2000 | 5,124 | 20,059 | 285,036,114 |
| Population - 1990 | 3,989 | 17,836 | 251,960,433 |
| Pop. 2000 to Now | 21.7% | -3.4% | 15.6% |
| Pop. 1990 to Now | 56.3% | 8.7% | 30.8% |
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| Population Density | 749.8 | 1,130.8 | 93.4 |
| Land Area | 8.4 | 17.2 | 3,531,905.4 |
| Water Area | 1.6 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Twin Lakes, WI | Lake Forest, IL | United States |
| Age 0 to 4 | 2.7% | 3.8% | 5.9% |
| Age 5 to 9 | 4.5% | 4.7% | 6.1% |
| Age 10 to 14 | 7.5% | 6.9% | 6.6% |
| Age 15 to 17 | 4.5% | 4.8% | 3.9% |
| Age 18 to 20 | 2.2% | 6.2% | 4.0% |
| Age 21 to 24 | 4.0% | 6.7% | 5.2% |
| Age 25 to 34 | 10.9% | 7.8% | 13.8% |
| Age 35 to 44 | 11.6% | 7.7% | 12.9% |
| Age 45 to 54 | 16.0% | 13.4% | 12.6% |
| Age 55 to 59 | 8.5% | 7.5% | 6.7% |
| Age 60 to 64 | 10.1% | 6.1% | 6.3% |
| Age 65 to 74 | 12.3% | 13.2% | 9.6% |
| Age 75 to 84 | 3.9% | 7.3% | 4.5% |
| Age 85 and over | 1.3% | 4.0% | 1.9% |
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| Race | | | |
| | Twin Lakes, WI | Lake Forest, IL | United States |
| White | 92.3% | 82.1% | 59.4% |
| Black | 0.5% | 1.0% | 12.2% |
| Asian | 0.0% | 7.2% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.8% | 0.4% |
| Two or More Races | 2.5% | 3.6% | 3.2% |
| Hispanic | 4.7% | 5.2% | 18.4% |
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| Marriage & Family | | | |
| | Twin Lakes, WI | Lake Forest, IL | United States |
| Married Population | 56.3% | 57.1% | 49.8% |
| Currently Married | 55.5% | 56.6% | 48.0% |
| Married but Separated | 0.8% | 0.5% | 1.8% |
| Single Population | 43.8% | 42.9% | 50.2% |
| Never Married | 28.0% | 30.5% | 33.8% |
| Divorced | 12.6% | 6.3% | 10.8% |
| Widowed | 3.1% | 6.1% | 5.6% |
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| Household Size | 2.30 | 2.61 | 2.60 |
| Households | 2,738 | 7,014 | 124,010,992 |
| Family Households | 2,040 | 5,085 | 80,755,759 |
| Married couple, w/children | 22.9% | 34.9% | 30.5% |
| Married couple, no children | 54.7% | 54.1% | 42.9% |
| Non Family Households | 698 | 1,929 | 43,255,233 |
| Single householder, w/children | 9.7% | 4.8% | 15.8% |
| Single householder, no children | 12.7% | 6.2% | 10.8% |