| | Swampscott, MA | Nashua, NH | United States |
| Population | 15,043 | 90,659 | 329,725,481 |
| Female Population | 53.4% | 49.4% | 50.5% |
| Male Population | 46.6% | 50.6% | 49.5% |
| Median Age | 45 | 39.6 | 38.4 |
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| Population - 2010 | 13,817 | 86,569 | 309,327,143 |
| Population - 2000 | 14,412 | 86,605 | 285,036,114 |
| Population - 1990 | 13,650 | 79,662 | 251,960,433 |
| Pop. 2000 to Now | 7.3% | 3.0% | 15.6% |
| Pop. 1990 to Now | 13.3% | 11.9% | 30.8% |
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| Population Density | 4,976.2 | 2,940.3 | 93.4 |
| Land Area | 3.0 | 30.8 | 3,531,905.4 |
| Water Area | 3.7 | 0.9 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Swampscott, MA | Nashua, NH | United States |
| Age 0 to 4 | 5.4% | 5.5% | 5.9% |
| Age 5 to 9 | 5.7% | 5.2% | 6.1% |
| Age 10 to 14 | 6.7% | 5.7% | 6.6% |
| Age 15 to 17 | 2.8% | 3.2% | 3.9% |
| Age 18 to 20 | 2.5% | 2.8% | 4.0% |
| Age 21 to 24 | 4.5% | 5.8% | 5.2% |
| Age 25 to 34 | 9.5% | 16.2% | 13.8% |
| Age 35 to 44 | 13.0% | 12.0% | 12.9% |
| Age 45 to 54 | 17.7% | 13.4% | 12.6% |
| Age 55 to 59 | 8.2% | 6.8% | 6.7% |
| Age 60 to 64 | 5.5% | 7.3% | 6.3% |
| Age 65 to 74 | 10.9% | 9.7% | 9.6% |
| Age 75 to 84 | 4.5% | 4.4% | 4.5% |
| Age 85 and over | 3.2% | 2.1% | 1.9% |
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| Race | | | |
| | Swampscott, MA | Nashua, NH | United States |
| White | 88.8% | 73.2% | 59.4% |
| Black | 1.2% | 2.2% | 12.2% |
| Asian | 2.6% | 8.0% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.3% | 0.2% | 0.4% |
| Two or More Races | 1.5% | 3.1% | 3.2% |
| Hispanic | 5.6% | 13.2% | 18.4% |
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| Marriage & Family | | | |
| | Swampscott, MA | Nashua, NH | United States |
| Married Population | 61.5% | 47.3% | 49.8% |
| Currently Married | 59.4% | 45.5% | 48.0% |
| Married but Separated | 2.1% | 1.8% | 1.8% |
| Single Population | 38.5% | 52.7% | 50.2% |
| Never Married | 23.4% | 33.7% | 33.8% |
| Divorced | 9.8% | 13.0% | 10.8% |
| Widowed | 5.3% | 6.0% | 5.6% |
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| Household Size | 2.45 | 2.40 | 2.60 |
| Households | 6,093 | 37,119 | 124,010,992 |
| Family Households | 4,172 | 21,905 | 80,755,759 |
| Married couple, w/children | 36.9% | 29.6% | 30.5% |
| Married couple, no children | 46.4% | 43.6% | 42.9% |
| Non Family Households | 1,921 | 15,214 | 43,255,233 |
| Single householder, w/children | 7.0% | 14.5% | 15.8% |
| Single householder, no children | 9.8% | 12.3% | 10.8% |