| | Wantagh, NY | Seaford, NY | United States |
| Population | 18,331 | 15,636 | 329,725,481 |
| Female Population | 49.2% | 49.2% | 50.5% |
| Male Population | 50.8% | 50.8% | 49.5% |
| Median Age | 40.3 | 41.8 | 38.4 |
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| Population - 2010 | 17,981 | 15,463 | 309,327,143 |
| Population - 2000 | 18,971 | 15,791 | 285,036,114 |
| Population - 1990 | 18,567 | 15,597 | 251,960,433 |
| Pop. 2000 to Now | -2.6% | -2.7% | 15.6% |
| Pop. 1990 to Now | -0.5% | -1.5% | 30.8% |
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| Population Density | 4,786.2 | 5,990.8 | 93.4 |
| Land Area | 3.8 | 2.6 | 3,531,905.4 |
| Water Area | 0.3 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Wantagh, NY | Seaford, NY | United States |
| Age 0 to 4 | 5.0% | 4.4% | 5.9% |
| Age 5 to 9 | 7.2% | 5.9% | 6.1% |
| Age 10 to 14 | 6.6% | 7.4% | 6.6% |
| Age 15 to 17 | 6.0% | 5.8% | 3.9% |
| Age 18 to 20 | 3.4% | 4.3% | 4.0% |
| Age 21 to 24 | 4.9% | 5.4% | 5.2% |
| Age 25 to 34 | 10.1% | 9.7% | 13.8% |
| Age 35 to 44 | 13.1% | 11.0% | 12.9% |
| Age 45 to 54 | 14.0% | 15.5% | 12.6% |
| Age 55 to 59 | 7.0% | 8.1% | 6.7% |
| Age 60 to 64 | 7.2% | 5.9% | 6.3% |
| Age 65 to 74 | 8.8% | 9.1% | 9.6% |
| Age 75 to 84 | 4.8% | 4.8% | 4.5% |
| Age 85 and over | 1.9% | 2.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Wantagh, NY | Seaford, NY | United States |
| White | 88.0% | 88.0% | 59.4% |
| Black | 1.1% | 0.9% | 12.2% |
| Asian | 1.6% | 3.7% | 5.6% |
| Native American | 0.1% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.6% | 0.1% | 0.4% |
| Two or More Races | 1.9% | 0.9% | 3.2% |
| Hispanic | 6.6% | 6.3% | 18.4% |
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| Marriage & Family | | | |
| | Wantagh, NY | Seaford, NY | United States |
| Married Population | 55.8% | 58.0% | 49.8% |
| Currently Married | 53.9% | 57.2% | 48.0% |
| Married but Separated | 1.9% | 0.9% | 1.8% |
| Single Population | 44.2% | 42.0% | 50.2% |
| Never Married | 30.9% | 29.3% | 33.8% |
| Divorced | 7.7% | 7.4% | 10.8% |
| Widowed | 5.7% | 5.2% | 5.6% |
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| Household Size | 3.12 | 3.03 | 2.60 |
| Households | 5,858 | 5,136 | 124,010,992 |
| Family Households | 4,802 | 4,288 | 80,755,759 |
| Married couple, w/children | 38.7% | 41.1% | 30.5% |
| Married couple, no children | 41.1% | 42.6% | 42.9% |
| Non Family Households | 1,056 | 848 | 43,255,233 |
| Single householder, w/children | 10.7% | 7.2% | 15.8% |
| Single householder, no children | 9.5% | 9.1% | 10.8% |