| | Somerset, MA | Darien, IL | United States |
| Population | 18,271 | 22,087 | 329,725,481 |
| Female Population | 51.7% | 50.0% | 50.5% |
| Male Population | 48.3% | 50.0% | 49.5% |
| Median Age | 46.4 | 44.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 18,202 | 22,062 | 309,327,143 |
| Population - 2000 | 18,234 | 22,860 | 285,036,114 |
| Population - 1990 | 17,655 | 18,341 | 251,960,433 |
| Pop. 2000 to Now | -0.5% | -5.8% | 15.6% |
| Pop. 1990 to Now | 2.8% | 17.4% | 30.8% |
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| Population Density | 2,312.8 | 3,561.3 | 93.4 |
| Land Area | 7.9 | 6.2 | 3,531,905.4 |
| Water Area | 4.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Somerset, MA | Darien, IL | United States |
| Age 0 to 4 | 3.9% | 3.2% | 5.9% |
| Age 5 to 9 | 5.2% | 5.5% | 6.1% |
| Age 10 to 14 | 7.0% | 6.1% | 6.6% |
| Age 15 to 17 | 3.2% | 3.9% | 3.9% |
| Age 18 to 20 | 2.5% | 2.6% | 4.0% |
| Age 21 to 24 | 3.7% | 4.8% | 5.2% |
| Age 25 to 34 | 10.4% | 11.8% | 13.8% |
| Age 35 to 44 | 11.0% | 12.7% | 12.9% |
| Age 45 to 54 | 15.0% | 12.2% | 12.6% |
| Age 55 to 59 | 7.6% | 8.0% | 6.7% |
| Age 60 to 64 | 6.0% | 7.7% | 6.3% |
| Age 65 to 74 | 13.0% | 14.1% | 9.6% |
| Age 75 to 84 | 5.9% | 5.4% | 4.5% |
| Age 85 and over | 5.6% | 1.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Somerset, MA | Darien, IL | United States |
| White | 94.4% | 73.9% | 59.4% |
| Black | 0.3% | 3.3% | 12.2% |
| Asian | 0.7% | 12.2% | 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 | 3.0% | 3.1% | 3.2% |
| Hispanic | 1.5% | 7.6% | 18.4% |
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| Marriage & Family | | | |
| | Somerset, MA | Darien, IL | United States |
| Married Population | 57.6% | 57.5% | 49.8% |
| Currently Married | 56.1% | 56.3% | 48.0% |
| Married but Separated | 1.5% | 1.2% | 1.8% |
| Single Population | 42.4% | 42.5% | 50.2% |
| Never Married | 24.8% | 26.7% | 33.8% |
| Divorced | 10.4% | 10.3% | 10.8% |
| Widowed | 7.1% | 5.4% | 5.6% |
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| Household Size | 2.49 | 2.52 | 2.60 |
| Households | 7,248 | 8,770 | 124,010,992 |
| Family Households | 5,333 | 6,340 | 80,755,759 |
| Married couple, w/children | 31.2% | 27.1% | 30.5% |
| Married couple, no children | 45.9% | 51.7% | 42.9% |
| Non Family Households | 1,915 | 2,430 | 43,255,233 |
| Single householder, w/children | 10.0% | 9.7% | 15.8% |
| Single householder, no children | 13.0% | 11.5% | 10.8% |