| | Mendon, MA | Holliston, MA | United States |
| Population | 6,212 | 14,891 | 329,725,481 |
| Female Population | 51.0% | 50.0% | 50.5% |
| Male Population | 49.0% | 50.0% | 49.5% |
| Median Age | 45.6 | 44.2 | 38.4 |
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| Population - 2010 | 5,859 | 13,584 | 309,327,143 |
| Population - 2000 | 5,286 | 13,801 | 285,036,114 |
| Population - 1990 | 4,010 | 12,926 | 251,960,433 |
| Pop. 2000 to Now | 17.9% | 7.8% | 15.6% |
| Pop. 1990 to Now | 55.4% | 15.1% | 30.8% |
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| Population Density | 349.5 | 798.7 | 93.4 |
| Land Area | 17.8 | 18.6 | 3,531,905.4 |
| Water Area | 0.2 | 0.4 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Mendon, MA | Holliston, MA | United States |
| Age 0 to 4 | 3.9% | 4.3% | 5.9% |
| Age 5 to 9 | 4.1% | 6.7% | 6.1% |
| Age 10 to 14 | 7.4% | 7.7% | 6.6% |
| Age 15 to 17 | 7.6% | 4.7% | 3.9% |
| Age 18 to 20 | 0.8% | 2.1% | 4.0% |
| Age 21 to 24 | 5.5% | 4.4% | 5.2% |
| Age 25 to 34 | 10.6% | 8.6% | 13.8% |
| Age 35 to 44 | 9.1% | 12.2% | 12.9% |
| Age 45 to 54 | 17.8% | 15.3% | 12.6% |
| Age 55 to 59 | 9.2% | 9.6% | 6.7% |
| Age 60 to 64 | 7.5% | 8.2% | 6.3% |
| Age 65 to 74 | 9.9% | 9.9% | 9.6% |
| Age 75 to 84 | 5.7% | 5.2% | 4.5% |
| Age 85 and over | 0.9% | 1.1% | 1.9% |
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| Race | | | |
| | Mendon, MA | Holliston, MA | United States |
| White | 92.8% | 87.0% | 59.4% |
| Black | 0.0% | 0.6% | 12.2% |
| Asian | 0.8% | 6.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.8% | 0.4% |
| Two or More Races | 4.0% | 1.7% | 3.2% |
| Hispanic | 2.4% | 3.1% | 18.4% |
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| Marriage & Family | | | |
| | Mendon, MA | Holliston, MA | United States |
| Married Population | 65.9% | 63.0% | 49.8% |
| Currently Married | 63.0% | 62.2% | 48.0% |
| Married but Separated | 2.9% | 0.8% | 1.8% |
| Single Population | 34.1% | 37.0% | 50.2% |
| Never Married | 26.7% | 23.7% | 33.8% |
| Divorced | 3.9% | 7.5% | 10.8% |
| Widowed | 3.5% | 5.8% | 5.6% |
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| Household Size | 2.98 | 2.70 | 2.60 |
| Households | 2,076 | 5,485 | 124,010,992 |
| Family Households | 1,767 | 4,322 | 80,755,759 |
| Married couple, w/children | 41.2% | 38.1% | 30.5% |
| Married couple, no children | 50.4% | 47.0% | 42.9% |
| Non Family Households | 309 | 1,163 | 43,255,233 |
| Single householder, w/children | 3.0% | 4.4% | 15.8% |
| Single householder, no children | 5.4% | 10.6% | 10.8% |