| | Plainfield, CT | Webster, MA | United States |
| Population | 14,991 | 17,664 | 329,725,481 |
| Female Population | 49.5% | 53.4% | 50.5% |
| Male Population | 50.5% | 46.6% | 49.5% |
| Median Age | 41.5 | 42 | 38.4 |
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| Population - 2010 | 15,400 | 16,786 | 309,327,143 |
| Population - 2000 | 14,619 | 16,415 | 285,036,114 |
| Population - 1990 | 14,363 | 16,196 | 251,960,433 |
| Pop. 2000 to Now | 3.2% | 2.5% | 15.6% |
| Pop. 1990 to Now | 5.0% | 3.9% | 30.8% |
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| Population Density | 353.8 | 1,426.8 | 93.4 |
| Land Area | 42.4 | 12.4 | 3,531,905.4 |
| Water Area | 0.6 | 2.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Plainfield, CT | Webster, MA | United States |
| Age 0 to 4 | 7.2% | 4.9% | 5.9% |
| Age 5 to 9 | 4.7% | 5.9% | 6.1% |
| Age 10 to 14 | 4.0% | 5.4% | 6.6% |
| Age 15 to 17 | 3.0% | 3.9% | 3.9% |
| Age 18 to 20 | 1.6% | 3.1% | 4.0% |
| Age 21 to 24 | 3.8% | 3.5% | 5.2% |
| Age 25 to 34 | 16.7% | 14.1% | 13.8% |
| Age 35 to 44 | 12.4% | 12.7% | 12.9% |
| Age 45 to 54 | 13.8% | 12.5% | 12.6% |
| Age 55 to 59 | 7.7% | 8.2% | 6.7% |
| Age 60 to 64 | 9.6% | 6.9% | 6.3% |
| Age 65 to 74 | 8.8% | 10.7% | 9.6% |
| Age 75 to 84 | 5.0% | 4.9% | 4.5% |
| Age 85 and over | 1.8% | 3.3% | 1.9% |
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| Race | | | |
| | Plainfield, CT | Webster, MA | United States |
| White | 89.3% | 78.3% | 59.4% |
| Black | 4.0% | 4.3% | 12.2% |
| Asian | 1.9% | 1.0% | 5.6% |
| Native American | 0.4% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.2% | 0.4% |
| Two or More Races | 1.5% | 1.4% | 3.2% |
| Hispanic | 2.9% | 14.4% | 18.4% |
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| Marriage & Family | | | |
| | Plainfield, CT | Webster, MA | United States |
| Married Population | 54.3% | 44.5% | 49.8% |
| Currently Married | 51.7% | 43.1% | 48.0% |
| Married but Separated | 2.6% | 1.4% | 1.8% |
| Single Population | 45.7% | 55.5% | 50.2% |
| Never Married | 29.6% | 34.4% | 33.8% |
| Divorced | 11.2% | 14.1% | 10.8% |
| Widowed | 5.0% | 7.1% | 5.6% |
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| Household Size | 2.45 | 2.34 | 2.60 |
| Households | 6,045 | 7,414 | 124,010,992 |
| Family Households | 4,016 | 4,603 | 80,755,759 |
| Married couple, w/children | 24.7% | 20.3% | 30.5% |
| Married couple, no children | 49.7% | 44.4% | 42.9% |
| Non Family Households | 2,029 | 2,811 | 43,255,233 |
| Single householder, w/children | 16.9% | 24.6% | 15.8% |
| Single householder, no children | 8.7% | 10.7% | 10.8% |