| | Harrison, NY | Ardsley, NY | United States |
| Population | 28,635 | 4,984 | 329,725,481 |
| Female Population | 52.8% | 50.6% | 50.5% |
| Male Population | 47.2% | 49.4% | 49.5% |
| Median Age | 35.1 | 43.2 | 38.4 |
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| Population - 2010 | 27,507 | 4,419 | 309,327,143 |
| Population - 2000 | 24,154 | 4,269 | 285,036,114 |
| Population - 1990 | 23,308 | 4,272 | 251,960,433 |
| Pop. 2000 to Now | 19.9% | 5.5% | 15.6% |
| Pop. 1990 to Now | 24.2% | 5.4% | 30.8% |
| space4 | | | |
| Population Density | 1,707.9 | 3,767.2 | 93.4 |
| Land Area | 16.8 | 1.3 | 3,531,905.4 |
| Water Area | 0.6 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Harrison, NY | Ardsley, NY | United States |
| Age 0 to 4 | 4.9% | 5.0% | 5.9% |
| Age 5 to 9 | 6.1% | 6.6% | 6.1% |
| Age 10 to 14 | 7.8% | 10.0% | 6.6% |
| Age 15 to 17 | 5.0% | 5.0% | 3.9% |
| Age 18 to 20 | 11.6% | 1.7% | 4.0% |
| Age 21 to 24 | 6.5% | 1.7% | 5.2% |
| Age 25 to 34 | 7.9% | 7.0% | 13.8% |
| Age 35 to 44 | 14.1% | 14.8% | 12.9% |
| Age 45 to 54 | 14.7% | 18.0% | 12.6% |
| Age 55 to 59 | 4.6% | 6.4% | 6.7% |
| Age 60 to 64 | 4.6% | 3.5% | 6.3% |
| Age 65 to 74 | 6.0% | 11.1% | 9.6% |
| Age 75 to 84 | 4.2% | 4.9% | 4.5% |
| Age 85 and over | 1.8% | 4.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Harrison, NY | Ardsley, NY | United States |
| White | 71.7% | 67.3% | 59.4% |
| Black | 4.9% | 3.9% | 12.2% |
| Asian | 6.6% | 12.7% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.3% | 0.4% |
| Two or More Races | 2.1% | 9.8% | 3.2% |
| Hispanic | 14.5% | 5.8% | 18.4% |
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| Marriage & Family | | | |
| | Harrison, NY | Ardsley, NY | United States |
| Married Population | 50.4% | 69.6% | 49.8% |
| Currently Married | 49.1% | 69.6% | 48.0% |
| Married but Separated | 1.3% | 0.0% | 1.8% |
| Single Population | 49.6% | 30.4% | 50.2% |
| Never Married | 40.7% | 21.9% | 33.8% |
| Divorced | 4.8% | 3.6% | 10.8% |
| Widowed | 4.0% | 4.9% | 5.6% |
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| Household Size | 3.08 | 3.06 | 2.60 |
| Households | 8,148 | 1,628 | 124,010,992 |
| Family Households | 6,373 | 1,449 | 80,755,759 |
| Married couple, w/children | 50.7% | 48.0% | 30.5% |
| Married couple, no children | 32.4% | 42.0% | 42.9% |
| Non Family Households | 1,775 | 179 | 43,255,233 |
| Single householder, w/children | 8.1% | 4.8% | 15.8% |
| Single householder, no children | 8.9% | 5.3% | 10.8% |