| | Madison, CT | Chantilly, VA | United States |
| Population | 17,742 | 23,564 | 329,725,481 |
| Female Population | 51.0% | 49.3% | 50.5% |
| Male Population | 49.0% | 50.7% | 49.5% |
| Median Age | 50.8 | 39.8 | 38.4 |
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| Population - 2010 | 18,267 | 22,120 | 309,327,143 |
| Population - 2000 | 17,858 | 41,041 | 285,036,114 |
| Population - 1990 | 15,485 | 29,337 | 251,960,433 |
| Pop. 2000 to Now | 0.4% | -39.1% | 15.6% |
| Pop. 1990 to Now | 15.8% | -14.7% | 30.8% |
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| Population Density | 490.8 | 1,963.3 | 93.4 |
| Land Area | 36.1 | 12.0 | 3,531,905.4 |
| Water Area | 0.5 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Madison, CT | Chantilly, VA | United States |
| Age 0 to 4 | 3.1% | 5.4% | 5.9% |
| Age 5 to 9 | 4.1% | 6.2% | 6.1% |
| Age 10 to 14 | 7.6% | 8.3% | 6.6% |
| Age 15 to 17 | 4.2% | 4.9% | 3.9% |
| Age 18 to 20 | 3.7% | 4.2% | 4.0% |
| Age 21 to 24 | 3.7% | 4.9% | 5.2% |
| Age 25 to 34 | 6.1% | 10.8% | 13.8% |
| Age 35 to 44 | 8.9% | 14.6% | 12.9% |
| Age 45 to 54 | 15.8% | 17.3% | 12.6% |
| Age 55 to 59 | 10.8% | 6.6% | 6.7% |
| Age 60 to 64 | 8.6% | 5.8% | 6.3% |
| Age 65 to 74 | 14.5% | 8.1% | 9.6% |
| Age 75 to 84 | 5.7% | 2.6% | 4.5% |
| Age 85 and over | 3.1% | 0.3% | 1.9% |
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| Race | | | |
| | Madison, CT | Chantilly, VA | United States |
| White | 90.0% | 33.2% | 59.4% |
| Black | 0.5% | 4.8% | 12.2% |
| Asian | 3.0% | 38.1% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.3% | 0.4% |
| Two or More Races | 3.5% | 2.5% | 3.2% |
| Hispanic | 2.8% | 21.2% | 18.4% |
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| Marriage & Family | | | |
| | Madison, CT | Chantilly, VA | United States |
| Married Population | 64.9% | 61.5% | 49.8% |
| Currently Married | 64.1% | 60.9% | 48.0% |
| Married but Separated | 0.8% | 0.7% | 1.8% |
| Single Population | 35.1% | 38.5% | 50.2% |
| Never Married | 23.1% | 30.5% | 33.8% |
| Divorced | 7.8% | 5.3% | 10.8% |
| Widowed | 4.2% | 2.6% | 5.6% |
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| Household Size | 2.61 | 3.30 | 2.60 |
| Households | 6,719 | 7,129 | 124,010,992 |
| Family Households | 5,221 | 5,968 | 80,755,759 |
| Married couple, w/children | 29.9% | 46.4% | 30.5% |
| Married couple, no children | 60.4% | 38.8% | 42.9% |
| Non Family Households | 1,498 | 1,161 | 43,255,233 |
| Single householder, w/children | 5.4% | 7.9% | 15.8% |
| Single householder, no children | 4.2% | 6.8% | 10.8% |