| | Billerica, MA | Dover, NH | United States |
| Population | 41,995 | 32,599 | 329,725,481 |
| Female Population | 49.1% | 50.7% | 50.5% |
| Male Population | 50.9% | 49.3% | 49.5% |
| Median Age | 43 | 36.2 | 38.4 |
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| Population - 2010 | 40,419 | 30,038 | 309,327,143 |
| Population - 2000 | 38,981 | 26,884 | 285,036,114 |
| Population - 1990 | 37,609 | 25,042 | 251,960,433 |
| Pop. 2000 to Now | 10.4% | 20.7% | 15.6% |
| Pop. 1990 to Now | 14.4% | 29.6% | 30.8% |
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| Population Density | 1,642.6 | 1,219.6 | 93.4 |
| Land Area | 25.6 | 26.7 | 3,531,905.4 |
| Water Area | 0.7 | 2.3 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Billerica, MA | Dover, NH | United States |
| Age 0 to 4 | 4.0% | 6.0% | 5.9% |
| Age 5 to 9 | 4.4% | 3.7% | 6.1% |
| Age 10 to 14 | 5.5% | 4.3% | 6.6% |
| Age 15 to 17 | 4.1% | 3.1% | 3.9% |
| Age 18 to 20 | 2.8% | 1.9% | 4.0% |
| Age 21 to 24 | 4.7% | 9.4% | 5.2% |
| Age 25 to 34 | 14.4% | 19.2% | 13.8% |
| Age 35 to 44 | 12.9% | 13.3% | 12.9% |
| Age 45 to 54 | 15.2% | 11.5% | 12.6% |
| Age 55 to 59 | 8.7% | 6.5% | 6.7% |
| Age 60 to 64 | 7.1% | 4.8% | 6.3% |
| Age 65 to 74 | 10.1% | 9.2% | 9.6% |
| Age 75 to 84 | 4.3% | 4.8% | 4.5% |
| Age 85 and over | 1.7% | 2.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Billerica, MA | Dover, NH | United States |
| White | 79.6% | 87.8% | 59.4% |
| Black | 6.2% | 1.0% | 12.2% |
| Asian | 7.2% | 4.4% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.0% | 0.2% |
| Other | 0.6% | 0.2% | 0.4% |
| Two or More Races | 1.9% | 3.1% | 3.2% |
| Hispanic | 4.3% | 3.4% | 18.4% |
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| Marriage & Family | | | |
| | Billerica, MA | Dover, NH | United States |
| Married Population | 52.8% | 49.9% | 49.8% |
| Currently Married | 51.3% | 48.5% | 48.0% |
| Married but Separated | 1.5% | 1.5% | 1.8% |
| Single Population | 47.2% | 50.1% | 50.2% |
| Never Married | 33.4% | 36.0% | 33.8% |
| Divorced | 8.9% | 10.4% | 10.8% |
| Widowed | 4.9% | 3.7% | 5.6% |
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| Household Size | 2.63 | 2.16 | 2.60 |
| Households | 15,498 | 14,707 | 124,010,992 |
| Family Households | 11,352 | 8,105 | 80,755,759 |
| Married couple, w/children | 33.2% | 31.2% | 30.5% |
| Married couple, no children | 44.2% | 50.0% | 42.9% |
| Non Family Households | 4,146 | 6,602 | 43,255,233 |
| Single householder, w/children | 7.2% | 9.5% | 15.8% |
| Single householder, no children | 15.5% | 9.2% | 10.8% |