| | Mattapoisett, MA | Smith Mills, MA | United States |
| Population | 6,478 | 4,846 | 329,725,481 |
| Female Population | 47.1% | 53.6% | 50.5% |
| Male Population | 52.9% | 46.5% | 49.5% |
| Median Age | 56.6 | 42.6 | 38.4 |
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| Population - 2010 | 6,055 | 4,825 | 309,327,143 |
| Population - 2000 | 6,268 | 4,432 | 285,036,114 |
| Population - 1990 | 5,850 | 4,593 | 251,960,433 |
| Pop. 2000 to Now | 2.5% | 5.8% | 15.6% |
| Pop. 1990 to Now | 9.9% | 2.1% | 30.8% |
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| Population Density | 373.2 | 1,038.8 | 93.4 |
| Land Area | 17.4 | 4.7 | 3,531,905.4 |
| Water Area | 6.8 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Mattapoisett, MA | Smith Mills, MA | United States |
| Age 0 to 4 | 3.1% | 2.6% | 5.9% |
| Age 5 to 9 | 3.8% | 5.3% | 6.1% |
| Age 10 to 14 | 6.5% | 7.3% | 6.6% |
| Age 15 to 17 | 2.5% | 5.9% | 3.9% |
| Age 18 to 20 | 3.4% | 1.7% | 4.0% |
| Age 21 to 24 | 4.8% | 2.2% | 5.2% |
| Age 25 to 34 | 6.8% | 15.0% | 13.8% |
| Age 35 to 44 | 8.8% | 14.3% | 12.9% |
| Age 45 to 54 | 8.8% | 15.5% | 12.6% |
| Age 55 to 59 | 12.6% | 6.0% | 6.7% |
| Age 60 to 64 | 11.4% | 4.4% | 6.3% |
| Age 65 to 74 | 13.5% | 9.2% | 9.6% |
| Age 75 to 84 | 8.0% | 5.7% | 4.5% |
| Age 85 and over | 5.9% | 4.9% | 1.9% |
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| Race | | | |
| | Mattapoisett, MA | Smith Mills, MA | United States |
| White | 92.2% | 90.2% | 59.4% |
| Black | 0.0% | 1.2% | 12.2% |
| Asian | 0.4% | 2.4% | 5.6% |
| Native American | 0.7% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 0.8% | 0.4% |
| Two or More Races | 5.4% | 2.5% | 3.2% |
| Hispanic | 0.9% | 3.0% | 18.4% |
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| Marriage & Family | | | |
| | Mattapoisett, MA | Smith Mills, MA | United States |
| Married Population | 63.7% | 53.4% | 49.8% |
| Currently Married | 63.7% | 52.7% | 48.0% |
| Married but Separated | 0.0% | 0.7% | 1.8% |
| Single Population | 36.3% | 46.6% | 50.2% |
| Never Married | 21.1% | 27.9% | 33.8% |
| Divorced | 8.6% | 9.1% | 10.8% |
| Widowed | 6.7% | 9.6% | 5.6% |
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| Household Size | 2.21 | 2.29 | 2.60 |
| Households | 2,926 | 2,109 | 124,010,992 |
| Family Households | 1,992 | 1,524 | 80,755,759 |
| Married couple, w/children | 25.3% | 32.5% | 30.5% |
| Married couple, no children | 64.1% | 36.8% | 42.9% |
| Non Family Households | 934 | 585 | 43,255,233 |
| Single householder, w/children | 3.5% | 23.0% | 15.8% |
| Single householder, no children | 7.2% | 7.7% | 10.8% |