| | Needham, MA | Walpole, NH | United States |
| Population | 31,808 | 3,655 | 329,725,481 |
| Female Population | 53.1% | 53.6% | 50.5% |
| Male Population | 46.9% | 46.4% | 49.5% |
| Median Age | 43.4 | 41.2 | 38.4 |
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| Population - 2010 | 29,170 | 3,730 | 309,327,143 |
| Population - 2000 | 28,911 | 3,594 | 285,036,114 |
| Population - 1990 | 27,557 | 3,210 | 251,960,433 |
| Pop. 2000 to Now | 9.1% | 12.2% | 15.6% |
| Pop. 1990 to Now | 14.4% | 25.6% | 30.8% |
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| Population Density | 2,589.0 | 103.9 | 93.4 |
| Land Area | 12.3 | 35.2 | 3,531,905.4 |
| Water Area | 0.4 | 1.5 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Needham, MA | Walpole, NH | United States |
| Age 0 to 4 | 4.9% | 9.9% | 5.9% |
| Age 5 to 9 | 8.5% | 4.7% | 6.1% |
| Age 10 to 14 | 9.0% | 5.4% | 6.6% |
| Age 15 to 17 | 5.3% | 3.9% | 3.9% |
| Age 18 to 20 | 3.0% | 1.9% | 4.0% |
| Age 21 to 24 | 3.3% | 2.4% | 5.2% |
| Age 25 to 34 | 4.9% | 16.9% | 13.8% |
| Age 35 to 44 | 13.8% | 8.6% | 12.9% |
| Age 45 to 54 | 14.2% | 13.8% | 12.6% |
| Age 55 to 59 | 7.9% | 5.1% | 6.7% |
| Age 60 to 64 | 6.5% | 6.5% | 6.3% |
| Age 65 to 74 | 9.7% | 12.3% | 9.6% |
| Age 75 to 84 | 4.9% | 4.5% | 4.5% |
| Age 85 and over | 4.0% | 4.0% | 1.9% |
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| Race | | | |
| | Needham, MA | Walpole, NH | United States |
| White | 81.6% | 96.0% | 59.4% |
| Black | 2.3% | 2.5% | 12.2% |
| Asian | 9.3% | 0.0% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.6% | 1.5% | 3.2% |
| Hispanic | 4.2% | 0.0% | 18.4% |
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| Marriage & Family | | | |
| | Needham, MA | Walpole, NH | United States |
| Married Population | 67.3% | 54.5% | 49.8% |
| Currently Married | 66.5% | 52.2% | 48.0% |
| Married but Separated | 0.8% | 2.3% | 1.8% |
| Single Population | 32.7% | 45.5% | 50.2% |
| Never Married | 22.0% | 25.3% | 33.8% |
| Divorced | 6.0% | 13.0% | 10.8% |
| Widowed | 4.7% | 7.2% | 5.6% |
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| Household Size | 2.76 | 2.52 | 2.60 |
| Households | 11,260 | 1,449 | 124,010,992 |
| Family Households | 9,005 | 894 | 80,755,759 |
| Married couple, w/children | 46.5% | 40.7% | 30.5% |
| Married couple, no children | 42.2% | 40.9% | 42.9% |
| Non Family Households | 2,255 | 555 | 43,255,233 |
| Single householder, w/children | 6.2% | 10.5% | 15.8% |
| Single householder, no children | 5.1% | 7.8% | 10.8% |