| | Oceanside, NY | Baldwin CDP (Nassau County), NY | United States |
| Population | 31,182 | 33,352 | 329,725,481 |
| Female Population | 48.9% | 50.9% | 50.5% |
| Male Population | 51.1% | 49.1% | 49.5% |
| Median Age | 45.7 | 42 | 38.4 |
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| Population - 2010 | 31,078 | 23,711 | 309,327,143 |
| Population - 2000 | 32,733 | 23,455 | 285,036,114 |
| Population - 1990 | 32,423 | 22,719 | 251,960,433 |
| Pop. 2000 to Now | -6.4% | 7.2% | 15.6% |
| Pop. 1990 to Now | -5.5% | 10.7% | 30.8% |
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| Population Density | 6,326.2 | 11,282.8 | 93.4 |
| Land Area | 4.9 | 3.0 | 3,531,905.4 |
| Water Area | 0.5 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Oceanside, NY | Baldwin CDP (Nassau County), NY | United States |
| Age 0 to 4 | 4.9% | 4.2% | 5.9% |
| Age 5 to 9 | 5.8% | 4.9% | 6.1% |
| Age 10 to 14 | 6.4% | 6.6% | 6.6% |
| Age 15 to 17 | 3.4% | 4.8% | 3.9% |
| Age 18 to 20 | 2.6% | 3.4% | 4.0% |
| Age 21 to 24 | 5.0% | 5.1% | 5.2% |
| Age 25 to 34 | 10.1% | 12.3% | 13.8% |
| Age 35 to 44 | 11.1% | 13.4% | 12.9% |
| Age 45 to 54 | 15.3% | 13.9% | 12.6% |
| Age 55 to 59 | 8.6% | 7.3% | 6.7% |
| Age 60 to 64 | 5.6% | 8.3% | 6.3% |
| Age 65 to 74 | 12.7% | 9.8% | 9.6% |
| Age 75 to 84 | 5.1% | 4.3% | 4.5% |
| Age 85 and over | 3.4% | 1.8% | 1.9% |
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| Race | | | |
| | Oceanside, NY | Baldwin CDP (Nassau County), NY | United States |
| White | 77.9% | 34.5% | 59.4% |
| Black | 1.5% | 37.2% | 12.2% |
| Asian | 3.5% | 3.5% | 5.6% |
| Native American | 0.5% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.0% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 1.1% | 5.6% | 3.2% |
| Hispanic | 15.4% | 19.2% | 18.4% |
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| Marriage & Family | | | |
| | Oceanside, NY | Baldwin CDP (Nassau County), NY | United States |
| Married Population | 61.2% | 50.8% | 49.8% |
| Currently Married | 59.7% | 48.9% | 48.0% |
| Married but Separated | 1.5% | 1.9% | 1.8% |
| Single Population | 38.8% | 49.2% | 50.2% |
| Never Married | 25.9% | 37.2% | 33.8% |
| Divorced | 5.8% | 7.2% | 10.8% |
| Widowed | 7.2% | 4.7% | 5.6% |
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| Household Size | 2.88 | 3.17 | 2.60 |
| Households | 10,781 | 10,492 | 124,010,992 |
| Family Households | 8,403 | 8,413 | 80,755,759 |
| Married couple, w/children | 34.9% | 32.0% | 30.5% |
| Married couple, no children | 49.3% | 43.9% | 42.9% |
| Non Family Households | 2,378 | 2,079 | 43,255,233 |
| Single householder, w/children | 5.9% | 10.8% | 15.8% |
| Single householder, no children | 9.8% | 13.3% | 10.8% |