| | Brookfield, CT | Gettysburg, PA | United States |
| Population | 17,428 | 7,423 | 329,725,481 |
| Female Population | 51.0% | 48.8% | 50.5% |
| Male Population | 49.0% | 51.2% | 49.5% |
| Median Age | 45.8 | 24.4 | 38.4 |
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| Population - 2010 | 16,469 | 7,595 | 309,327,143 |
| Population - 2000 | 15,664 | 7,490 | 285,036,114 |
| Population - 1990 | 14,113 | 7,025 | 251,960,433 |
| Pop. 2000 to Now | 7.9% | 2.9% | 15.6% |
| Pop. 1990 to Now | 19.8% | 9.7% | 30.8% |
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| Population Density | 881.4 | 4,471.7 | 93.4 |
| Land Area | 19.8 | 1.7 | 3,531,905.4 |
| Water Area | 0.6 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Brookfield, CT | Gettysburg, PA | United States |
| Age 0 to 4 | 4.8% | 2.7% | 5.9% |
| Age 5 to 9 | 5.4% | 2.5% | 6.1% |
| Age 10 to 14 | 6.1% | 3.6% | 6.6% |
| Age 15 to 17 | 6.3% | 3.1% | 3.9% |
| Age 18 to 20 | 2.3% | 29.2% | 4.0% |
| Age 21 to 24 | 5.0% | 9.1% | 5.2% |
| Age 25 to 34 | 9.3% | 12.3% | 13.8% |
| Age 35 to 44 | 10.3% | 9.9% | 12.9% |
| Age 45 to 54 | 16.1% | 8.2% | 12.6% |
| Age 55 to 59 | 9.1% | 3.6% | 6.7% |
| Age 60 to 64 | 6.0% | 4.4% | 6.3% |
| Age 65 to 74 | 11.0% | 6.2% | 9.6% |
| Age 75 to 84 | 5.9% | 4.0% | 4.5% |
| Age 85 and over | 2.5% | 1.1% | 1.9% |
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| Race | | | |
| | Brookfield, CT | Gettysburg, PA | United States |
| White | 83.3% | 75.3% | 59.4% |
| Black | 2.8% | 3.8% | 12.2% |
| Asian | 4.2% | 2.5% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.0% | 0.2% |
| Other | 0.2% | 0.0% | 0.4% |
| Two or More Races | 3.0% | 2.9% | 3.2% |
| Hispanic | 6.5% | 15.5% | 18.4% |
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| Marriage & Family | | | |
| | Brookfield, CT | Gettysburg, PA | United States |
| Married Population | 59.6% | 26.2% | 49.8% |
| Currently Married | 59.2% | 24.9% | 48.0% |
| Married but Separated | 0.3% | 1.2% | 1.8% |
| Single Population | 40.4% | 73.8% | 50.2% |
| Never Married | 26.2% | 59.2% | 33.8% |
| Divorced | 8.2% | 12.1% | 10.8% |
| Widowed | 6.0% | 2.6% | 5.6% |
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| Household Size | 2.74 | 2.08 | 2.60 |
| Households | 6,330 | 2,304 | 124,010,992 |
| Family Households | 5,011 | 1,143 | 80,755,759 |
| Married couple, w/children | 34.9% | 21.2% | 30.5% |
| Married couple, no children | 47.8% | 46.5% | 42.9% |
| Non Family Households | 1,319 | 1,161 | 43,255,233 |
| Single householder, w/children | 7.0% | 12.2% | 15.8% |
| Single householder, no children | 10.3% | 20.0% | 10.8% |