| | Chelsea, MA | Newark, DE | United States |
| Population | 40,025 | 31,393 | 329,725,481 |
| Female Population | 48.8% | 52.6% | 50.5% |
| Male Population | 51.3% | 47.4% | 49.5% |
| Median Age | 33.6 | 22.7 | 38.4 |
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| Population - 2010 | 35,344 | 31,778 | 309,327,143 |
| Population - 2000 | 35,080 | 28,547 | 285,036,114 |
| Population - 1990 | 28,710 | 25,098 | 251,960,433 |
| Pop. 2000 to Now | 11.8% | 18.6% | 15.6% |
| Pop. 1990 to Now | 36.6% | 34.9% | 30.8% |
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| Population Density | 18,070.0 | 3,416.0 | 93.4 |
| Land Area | 2.2 | 9.2 | 3,531,905.4 |
| Water Area | 0.2 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Chelsea, MA | Newark, DE | United States |
| Age 0 to 4 | 8.5% | 2.4% | 5.9% |
| Age 5 to 9 | 5.5% | 4.0% | 6.1% |
| Age 10 to 14 | 7.2% | 3.1% | 6.6% |
| Age 15 to 17 | 4.1% | 2.8% | 3.9% |
| Age 18 to 20 | 3.5% | 28.2% | 4.0% |
| Age 21 to 24 | 4.9% | 14.1% | 5.2% |
| Age 25 to 34 | 18.9% | 12.9% | 13.8% |
| Age 35 to 44 | 15.8% | 6.0% | 12.9% |
| Age 45 to 54 | 11.7% | 6.5% | 12.6% |
| Age 55 to 59 | 5.3% | 3.8% | 6.7% |
| Age 60 to 64 | 5.1% | 4.1% | 6.3% |
| Age 65 to 74 | 5.4% | 6.2% | 9.6% |
| Age 75 to 84 | 2.5% | 4.1% | 4.5% |
| Age 85 and over | 1.7% | 1.7% | 1.9% |
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| Race | | | |
| | Chelsea, MA | Newark, DE | United States |
| White | 19.7% | 68.2% | 59.4% |
| Black | 7.0% | 8.5% | 12.2% |
| Asian | 3.5% | 7.8% | 5.6% |
| Native American | 0.0% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.4% | 0.4% | 0.4% |
| Two or More Races | 3.3% | 3.7% | 3.2% |
| Hispanic | 66.1% | 11.1% | 18.4% |
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| Marriage & Family | | | |
| | Chelsea, MA | Newark, DE | United States |
| Married Population | 41.5% | 28.4% | 49.8% |
| Currently Married | 36.9% | 27.8% | 48.0% |
| Married but Separated | 4.6% | 0.5% | 1.8% |
| Single Population | 58.5% | 71.6% | 50.2% |
| Never Married | 44.7% | 63.5% | 33.8% |
| Divorced | 8.4% | 4.7% | 10.8% |
| Widowed | 5.5% | 3.5% | 5.6% |
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| Household Size | 2.94 | 2.53 | 2.60 |
| Households | 13,353 | 9,546 | 124,010,992 |
| Family Households | 7,470 | 4,352 | 80,755,759 |
| Married couple, w/children | 34.0% | 31.0% | 30.5% |
| Married couple, no children | 26.6% | 52.3% | 42.9% |
| Non Family Households | 5,883 | 5,194 | 43,255,233 |
| Single householder, w/children | 25.3% | 8.4% | 15.8% |
| Single householder, no children | 14.1% | 8.4% | 10.8% |