| | Middlesex, VT | Walpole, NH | United States |
| Population | 1,889 | 3,655 | 329,725,481 |
| Female Population | 47.5% | 53.6% | 50.5% |
| Male Population | 52.5% | 46.4% | 49.5% |
| Median Age | 44.5 | 41.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,729 | 3,730 | 309,327,143 |
| Population - 2000 | 1,729 | 3,594 | 285,036,114 |
| Population - 1990 | 1,514 | 3,210 | 251,960,433 |
| Pop. 2000 to Now | -0.3% | 12.2% | 15.6% |
| Pop. 1990 to Now | 13.9% | 25.6% | 30.8% |
| space4 | | | |
| Population Density | 47.7 | 103.9 | 93.4 |
| Land Area | 39.6 | 35.2 | 3,531,905.4 |
| Water Area | 0.3 | 1.5 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Middlesex, VT | Walpole, NH | United States |
| Age 0 to 4 | 3.9% | 9.9% | 5.9% |
| Age 5 to 9 | 6.0% | 4.7% | 6.1% |
| Age 10 to 14 | 7.8% | 5.4% | 6.6% |
| Age 15 to 17 | 4.8% | 3.9% | 3.9% |
| Age 18 to 20 | 4.7% | 1.9% | 4.0% |
| Age 21 to 24 | 2.2% | 2.4% | 5.2% |
| Age 25 to 34 | 8.7% | 16.9% | 13.8% |
| Age 35 to 44 | 12.5% | 8.6% | 12.9% |
| Age 45 to 54 | 14.7% | 13.8% | 12.6% |
| Age 55 to 59 | 6.4% | 5.1% | 6.7% |
| Age 60 to 64 | 7.7% | 6.5% | 6.3% |
| Age 65 to 74 | 14.0% | 12.3% | 9.6% |
| Age 75 to 84 | 6.1% | 4.5% | 4.5% |
| Age 85 and over | 0.5% | 4.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Middlesex, VT | Walpole, NH | United States |
| White | 96.2% | 96.0% | 59.4% |
| Black | 0.2% | 2.5% | 12.2% |
| Asian | 0.4% | 0.0% | 5.6% |
| Native American | 1.5% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.3% | 0.0% | 0.4% |
| Two or More Races | 1.1% | 1.5% | 3.2% |
| Hispanic | 0.4% | 0.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Middlesex, VT | Walpole, NH | United States |
| Married Population | 54.2% | 54.5% | 49.8% |
| Currently Married | 54.1% | 52.2% | 48.0% |
| Married but Separated | 0.1% | 2.3% | 1.8% |
| Single Population | 45.8% | 45.5% | 50.2% |
| Never Married | 25.3% | 25.3% | 33.8% |
| Divorced | 17.9% | 13.0% | 10.8% |
| Widowed | 2.6% | 7.2% | 5.6% |
| space5 | | | |
| Household Size | 2.65 | 2.52 | 2.60 |
| Households | 714 | 1,449 | 124,010,992 |
| Family Households | 478 | 894 | 80,755,759 |
| Married couple, w/children | 27.8% | 40.7% | 30.5% |
| Married couple, no children | 51.5% | 40.9% | 42.9% |
| Non Family Households | 236 | 555 | 43,255,233 |
| Single householder, w/children | 18.4% | 10.5% | 15.8% |
| Single householder, no children | 2.3% | 7.8% | 10.8% |