| | Merrimac, MA | West Dundee, IL | United States |
| Population | 6,698 | 7,797 | 329,725,481 |
| Female Population | 48.1% | 47.9% | 50.5% |
| Male Population | 51.9% | 52.2% | 49.5% |
| Median Age | 48.2 | 36.6 | 38.4 |
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| Population - 2010 | 6,369 | 7,301 | 309,327,143 |
| Population - 2000 | 6,138 | 5,428 | 285,036,114 |
| Population - 1990 | 5,166 | 3,728 | 251,960,433 |
| Pop. 2000 to Now | 13.6% | 61.5% | 15.6% |
| Pop. 1990 to Now | 35.0% | 135.2% | 30.8% |
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| Population Density | 791.9 | 2,093.7 | 93.4 |
| Land Area | 8.5 | 3.7 | 3,531,905.4 |
| Water Area | 0.4 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Merrimac, MA | West Dundee, IL | United States |
| Age 0 to 4 | 6.4% | 7.6% | 5.9% |
| Age 5 to 9 | 7.1% | 5.3% | 6.1% |
| Age 10 to 14 | 3.1% | 5.4% | 6.6% |
| Age 15 to 17 | 3.1% | 3.4% | 3.9% |
| Age 18 to 20 | 3.6% | 3.1% | 4.0% |
| Age 21 to 24 | 5.3% | 6.8% | 5.2% |
| Age 25 to 34 | 8.5% | 16.4% | 13.8% |
| Age 35 to 44 | 8.1% | 9.4% | 12.9% |
| Age 45 to 54 | 17.2% | 18.4% | 12.6% |
| Age 55 to 59 | 11.2% | 7.2% | 6.7% |
| Age 60 to 64 | 6.4% | 6.1% | 6.3% |
| Age 65 to 74 | 10.6% | 6.5% | 9.6% |
| Age 75 to 84 | 7.8% | 4.0% | 4.5% |
| Age 85 and over | 1.5% | 0.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Merrimac, MA | West Dundee, IL | United States |
| White | 92.4% | 80.8% | 59.4% |
| Black | 0.0% | 1.8% | 12.2% |
| Asian | 1.1% | 6.0% | 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 | 5.1% | 0.8% | 3.2% |
| Hispanic | 1.4% | 10.7% | 18.4% |
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| Marriage & Family | | | |
| | Merrimac, MA | West Dundee, IL | United States |
| Married Population | 54.7% | 51.4% | 49.8% |
| Currently Married | 54.3% | 50.1% | 48.0% |
| Married but Separated | 0.4% | 1.3% | 1.8% |
| Single Population | 45.3% | 48.6% | 50.2% |
| Never Married | 28.0% | 37.0% | 33.8% |
| Divorced | 13.8% | 7.7% | 10.8% |
| Widowed | 3.5% | 3.9% | 5.6% |
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| Household Size | 2.58 | 2.51 | 2.60 |
| Households | 2,589 | 3,102 | 124,010,992 |
| Family Households | 1,758 | 1,995 | 80,755,759 |
| Married couple, w/children | 27.9% | 34.7% | 30.5% |
| Married couple, no children | 52.4% | 41.8% | 42.9% |
| Non Family Households | 831 | 1,107 | 43,255,233 |
| Single householder, w/children | 12.9% | 9.4% | 15.8% |
| Single householder, no children | 6.8% | 14.0% | 10.8% |