| | Harwich, MA | Keene, NH | United States |
| Population | 13,329 | 22,969 | 329,725,481 |
| Female Population | 51.9% | 50.4% | 50.5% |
| Male Population | 48.1% | 49.6% | 49.5% |
| Median Age | 58.4 | 36.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 12,234 | 23,518 | 309,327,143 |
| Population - 2000 | 12,386 | 22,563 | 285,036,114 |
| Population - 1990 | 10,275 | 22,430 | 251,960,433 |
| Pop. 2000 to Now | -2.0% | 0.6% | 15.6% |
| Pop. 1990 to Now | 18.2% | 1.2% | 30.8% |
| space4 | | | |
| Population Density | 638.2 | 618.9 | 93.4 |
| Land Area | 20.9 | 37.1 | 3,531,905.4 |
| Water Area | 12.2 | 0.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Harwich, MA | Keene, NH | United States |
| Age 0 to 4 | 2.1% | 3.0% | 5.9% |
| Age 5 to 9 | 2.4% | 3.6% | 6.1% |
| Age 10 to 14 | 5.0% | 4.6% | 6.6% |
| Age 15 to 17 | 2.8% | 3.1% | 3.9% |
| Age 18 to 20 | 1.9% | 11.5% | 4.0% |
| Age 21 to 24 | 4.8% | 9.4% | 5.2% |
| Age 25 to 34 | 6.4% | 13.1% | 13.8% |
| Age 35 to 44 | 10.6% | 10.4% | 12.9% |
| Age 45 to 54 | 8.1% | 12.4% | 12.6% |
| Age 55 to 59 | 8.8% | 6.8% | 6.7% |
| Age 60 to 64 | 11.9% | 4.0% | 6.3% |
| Age 65 to 74 | 21.9% | 9.3% | 9.6% |
| Age 75 to 84 | 8.6% | 4.9% | 4.5% |
| Age 85 and over | 4.5% | 3.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Harwich, MA | Keene, NH | United States |
| White | 93.9% | 91.5% | 59.4% |
| Black | 1.6% | 1.1% | 12.2% |
| Asian | 0.3% | 0.5% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 1.5% | 0.3% | 0.4% |
| Two or More Races | 0.9% | 3.0% | 3.2% |
| Hispanic | 1.8% | 3.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Harwich, MA | Keene, NH | United States |
| Married Population | 50.8% | 35.2% | 49.8% |
| Currently Married | 50.1% | 34.0% | 48.0% |
| Married but Separated | 0.7% | 1.2% | 1.8% |
| Single Population | 49.2% | 64.8% | 50.2% |
| Never Married | 23.6% | 45.0% | 33.8% |
| Divorced | 15.5% | 13.2% | 10.8% |
| Widowed | 10.1% | 6.5% | 5.6% |
| space5 | | | |
| Household Size | 2.29 | 2.20 | 2.60 |
| Households | 5,733 | 9,130 | 124,010,992 |
| Family Households | 3,421 | 4,537 | 80,755,759 |
| Married couple, w/children | 14.8% | 20.7% | 30.5% |
| Married couple, no children | 64.6% | 51.8% | 42.9% |
| Non Family Households | 2,312 | 4,593 | 43,255,233 |
| Single householder, w/children | 8.3% | 16.6% | 15.8% |
| Single householder, no children | 12.3% | 11.0% | 10.8% |