| | Salem, MA | Frederick, MD | United States |
| Population | 44,452 | 76,376 | 329,725,481 |
| Female Population | 55.1% | 51.0% | 50.5% |
| Male Population | 44.9% | 49.0% | 49.5% |
| Median Age | 37.6 | 36.9 | 38.4 |
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| Population - 2010 | 41,823 | 65,508 | 309,327,143 |
| Population - 2000 | 40,407 | 52,767 | 285,036,114 |
| Population - 1990 | 38,091 | 40,148 | 251,960,433 |
| Pop. 2000 to Now | 7.9% | 38.9% | 15.6% |
| Pop. 1990 to Now | 14.4% | 82.6% | 30.8% |
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| Population Density | 5,359.5 | 3,297.3 | 93.4 |
| Land Area | 8.3 | 23.2 | 3,531,905.4 |
| Water Area | 10.0 | 0.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Salem, MA | Frederick, MD | United States |
| Age 0 to 4 | 5.1% | 5.9% | 5.9% |
| Age 5 to 9 | 4.1% | 5.8% | 6.1% |
| Age 10 to 14 | 4.2% | 6.7% | 6.6% |
| Age 15 to 17 | 2.0% | 3.7% | 3.9% |
| Age 18 to 20 | 4.5% | 3.6% | 4.0% |
| Age 21 to 24 | 7.8% | 5.5% | 5.2% |
| Age 25 to 34 | 18.2% | 15.7% | 13.8% |
| Age 35 to 44 | 13.5% | 14.3% | 12.9% |
| Age 45 to 54 | 11.6% | 13.1% | 12.6% |
| Age 55 to 59 | 6.8% | 6.9% | 6.7% |
| Age 60 to 64 | 6.0% | 5.0% | 6.3% |
| Age 65 to 74 | 9.6% | 8.0% | 9.6% |
| Age 75 to 84 | 4.2% | 3.9% | 4.5% |
| Age 85 and over | 2.3% | 1.8% | 1.9% |
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| Race | | | |
| | Salem, MA | Frederick, MD | United States |
| White | 72.0% | 54.9% | 59.4% |
| Black | 3.8% | 17.1% | 12.2% |
| Asian | 3.0% | 5.1% | 5.6% |
| Native American | 0.1% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 0.2% | 0.4% |
| Two or More Races | 2.9% | 4.9% | 3.2% |
| Hispanic | 17.7% | 17.5% | 18.4% |
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| Marriage & Family | | | |
| | Salem, MA | Frederick, MD | United States |
| Married Population | 41.5% | 47.9% | 49.8% |
| Currently Married | 39.5% | 45.7% | 48.0% |
| Married but Separated | 2.0% | 2.2% | 1.8% |
| Single Population | 58.5% | 52.1% | 50.2% |
| Never Married | 43.5% | 35.0% | 33.8% |
| Divorced | 10.6% | 11.7% | 10.8% |
| Widowed | 4.4% | 5.4% | 5.6% |
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| Household Size | 2.17 | 2.43 | 2.60 |
| Households | 19,745 | 30,644 | 124,010,992 |
| Family Households | 10,225 | 18,686 | 80,755,759 |
| Married couple, w/children | 22.9% | 34.7% | 30.5% |
| Married couple, no children | 44.9% | 35.7% | 42.9% |
| Non Family Households | 9,520 | 11,958 | 43,255,233 |
| Single householder, w/children | 18.2% | 18.2% | 15.8% |
| Single householder, no children | 14.0% | 11.4% | 10.8% |