| | Harrisburg, NC | Frederick, MD | United States |
| Population | 18,415 | 76,376 | 329,725,481 |
| Female Population | 54.8% | 51.0% | 50.5% |
| Male Population | 45.2% | 49.0% | 49.5% |
| Median Age | 35.9 | 36.9 | 38.4 |
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| Population - 2010 | 13,382 | 65,508 | 309,327,143 |
| Population - 2000 | 4,493 | 52,767 | 285,036,114 |
| Population - 1990 | 1,625 | 40,148 | 251,960,433 |
| Pop. 2000 to Now | 275.1% | 38.9% | 15.6% |
| Pop. 1990 to Now | 937.1% | 82.6% | 30.8% |
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| Population Density | 1,670.8 | 3,297.3 | 93.4 |
| Land Area | 11.0 | 23.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Harrisburg, NC | Frederick, MD | United States |
| Age 0 to 4 | 6.1% | 5.9% | 5.9% |
| Age 5 to 9 | 9.3% | 5.8% | 6.1% |
| Age 10 to 14 | 8.7% | 6.7% | 6.6% |
| Age 15 to 17 | 6.0% | 3.7% | 3.9% |
| Age 18 to 20 | 4.5% | 3.6% | 4.0% |
| Age 21 to 24 | 5.0% | 5.5% | 5.2% |
| Age 25 to 34 | 8.7% | 15.7% | 13.8% |
| Age 35 to 44 | 14.4% | 14.3% | 12.9% |
| Age 45 to 54 | 19.1% | 13.1% | 12.6% |
| Age 55 to 59 | 5.4% | 6.9% | 6.7% |
| Age 60 to 64 | 4.2% | 5.0% | 6.3% |
| Age 65 to 74 | 5.6% | 8.0% | 9.6% |
| Age 75 to 84 | 2.2% | 3.9% | 4.5% |
| Age 85 and over | 0.8% | 1.8% | 1.9% |
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| Race | | | |
| | Harrisburg, NC | Frederick, MD | United States |
| White | 59.0% | 54.9% | 59.4% |
| Black | 16.8% | 17.1% | 12.2% |
| Asian | 10.8% | 5.1% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 4.4% | 4.9% | 3.2% |
| Hispanic | 9.0% | 17.5% | 18.4% |
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| Marriage & Family | | | |
| | Harrisburg, NC | Frederick, MD | United States |
| Married Population | 60.7% | 47.9% | 49.8% |
| Currently Married | 59.3% | 45.7% | 48.0% |
| Married but Separated | 1.3% | 2.2% | 1.8% |
| Single Population | 39.3% | 52.1% | 50.2% |
| Never Married | 30.9% | 35.0% | 33.8% |
| Divorced | 5.0% | 11.7% | 10.8% |
| Widowed | 3.5% | 5.4% | 5.6% |
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| Household Size | 3.55 | 2.43 | 2.60 |
| Households | 5,171 | 30,644 | 124,010,992 |
| Family Households | 4,489 | 18,686 | 80,755,759 |
| Married couple, w/children | 52.6% | 34.7% | 30.5% |
| Married couple, no children | 33.5% | 35.7% | 42.9% |
| Non Family Households | 682 | 11,958 | 43,255,233 |
| Single householder, w/children | 8.6% | 18.2% | 15.8% |
| Single householder, no children | 5.3% | 11.4% | 10.8% |