| | Washington, MA | Peru, MA | United States |
| Population | 501 | 744 | 329,725,481 |
| Female Population | 46.9% | 46.0% | 50.5% |
| Male Population | 53.1% | 54.0% | 49.5% |
| Median Age | 61.8 | 49.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 542 | 848 | 309,327,143 |
| Population - 2000 | 544 | 821 | 285,036,114 |
| Population - 1990 | 615 | 779 | 251,960,433 |
| Pop. 2000 to Now | -0.6% | 1.5% | 15.6% |
| Pop. 1990 to Now | -12.0% | 6.9% | 30.8% |
| space4 | | | |
| Population Density | 13.2 | 28.7 | 93.4 |
| Land Area | 38.0 | 25.9 | 3,531,905.4 |
| Water Area | 0.8 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Washington, MA | Peru, MA | United States |
| Age 0 to 4 | 2.4% | 4.2% | 5.9% |
| Age 5 to 9 | 2.4% | 5.0% | 6.1% |
| Age 10 to 14 | 7.4% | 3.9% | 6.6% |
| Age 15 to 17 | 1.8% | 2.8% | 3.9% |
| Age 18 to 20 | 0.6% | 2.8% | 4.0% |
| Age 21 to 24 | 0.6% | 1.2% | 5.2% |
| Age 25 to 34 | 4.4% | 10.9% | 13.8% |
| Age 35 to 44 | 4.0% | 8.9% | 12.9% |
| Age 45 to 54 | 14.8% | 22.3% | 12.6% |
| Age 55 to 59 | 7.4% | 8.6% | 6.7% |
| Age 60 to 64 | 15.6% | 10.1% | 6.3% |
| Age 65 to 74 | 28.7% | 17.5% | 9.6% |
| Age 75 to 84 | 8.4% | 1.6% | 4.5% |
| Age 85 and over | 1.6% | 0.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Washington, MA | Peru, MA | United States |
| White | 88.8% | 95.0% | 59.4% |
| Black | 3.2% | 0.5% | 12.2% |
| Asian | 2.6% | 0.0% | 5.6% |
| Native American | 1.4% | 1.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 3.8% | 1.5% | 3.2% |
| Hispanic | 0.2% | 1.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Washington, MA | Peru, MA | United States |
| Married Population | 71.4% | 63.4% | 49.8% |
| Currently Married | 69.8% | 62.1% | 48.0% |
| Married but Separated | 1.6% | 1.2% | 1.8% |
| Single Population | 28.6% | 36.6% | 50.2% |
| Never Married | 13.2% | 24.6% | 33.8% |
| Divorced | 9.5% | 10.0% | 10.8% |
| Widowed | 5.9% | 2.0% | 5.6% |
| space5 | | | |
| Household Size | 2.04 | 2.29 | 2.60 |
| Households | 246 | 325 | 124,010,992 |
| Family Households | 169 | 225 | 80,755,759 |
| Married couple, w/children | 14.2% | 20.9% | 30.5% |
| Married couple, no children | 75.7% | 65.3% | 42.9% |
| Non Family Households | 77 | 100 | 43,255,233 |
| Single householder, w/children | 7.1% | 7.1% | 15.8% |
| Single householder, no children | 3.0% | 6.7% | 10.8% |