| | Syosset, NY | Elmont, NY | United States |
| Population | 19,347 | 36,741 | 329,725,481 |
| Female Population | 49.1% | 50.4% | 50.5% |
| Male Population | 50.9% | 49.6% | 49.5% |
| Median Age | 43.2 | 39.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 18,905 | 34,486 | 309,327,143 |
| Population - 2000 | 18,544 | 32,657 | 285,036,114 |
| Population - 1990 | 18,967 | 28,612 | 251,960,433 |
| Pop. 2000 to Now | 5.8% | 11.9% | 15.6% |
| Pop. 1990 to Now | 3.4% | 27.7% | 30.8% |
| space4 | | | |
| Population Density | 3,888.8 | 10,774.5 | 93.4 |
| Land Area | 5.0 | 3.4 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Syosset, NY | Elmont, NY | United States |
| Age 0 to 4 | 3.2% | 5.6% | 5.9% |
| Age 5 to 9 | 6.8% | 3.6% | 6.1% |
| Age 10 to 14 | 10.4% | 6.5% | 6.6% |
| Age 15 to 17 | 7.7% | 3.5% | 3.9% |
| Age 18 to 20 | 1.6% | 3.8% | 4.0% |
| Age 21 to 24 | 3.9% | 5.2% | 5.2% |
| Age 25 to 34 | 7.4% | 16.0% | 13.8% |
| Age 35 to 44 | 11.6% | 12.7% | 12.9% |
| Age 45 to 54 | 18.6% | 14.0% | 12.6% |
| Age 55 to 59 | 6.5% | 6.5% | 6.7% |
| Age 60 to 64 | 6.1% | 7.0% | 6.3% |
| Age 65 to 74 | 10.6% | 10.0% | 9.6% |
| Age 75 to 84 | 3.6% | 3.3% | 4.5% |
| Age 85 and over | 1.8% | 2.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Syosset, NY | Elmont, NY | United States |
| White | 63.9% | 14.0% | 59.4% |
| Black | 1.0% | 43.4% | 12.2% |
| Asian | 29.1% | 13.8% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.5% | 1.5% | 0.4% |
| Two or More Races | 1.4% | 5.4% | 3.2% |
| Hispanic | 4.0% | 21.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Syosset, NY | Elmont, NY | United States |
| Married Population | 66.2% | 47.9% | 49.8% |
| Currently Married | 65.6% | 46.2% | 48.0% |
| Married but Separated | 0.6% | 1.7% | 1.8% |
| Single Population | 33.8% | 52.1% | 50.2% |
| Never Married | 27.1% | 38.5% | 33.8% |
| Divorced | 3.2% | 7.9% | 10.8% |
| Widowed | 3.6% | 5.8% | 5.6% |
| space5 | | | |
| Household Size | 3.09 | 3.67 | 2.60 |
| Households | 6,204 | 10,009 | 124,010,992 |
| Family Households | 5,235 | 8,374 | 80,755,759 |
| Married couple, w/children | 52.7% | 36.7% | 30.5% |
| Married couple, no children | 39.5% | 31.6% | 42.9% |
| Non Family Households | 969 | 1,635 | 43,255,233 |
| Single householder, w/children | 2.8% | 12.1% | 15.8% |
| Single householder, no children | 5.0% | 19.6% | 10.8% |