| | Shelter Island, NY | Hornell, NY | United States |
| Population | 3,661 | 8,284 | 329,725,481 |
| Female Population | 45.7% | 49.4% | 50.5% |
| Male Population | 54.3% | 50.6% | 49.5% |
| Median Age | 51.3 | 41.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,398 | 8,586 | 309,327,143 |
| Population - 2000 | 2,228 | 9,019 | 285,036,114 |
| Population - 1990 | 2,263 | 9,877 | 251,960,433 |
| Pop. 2000 to Now | 8.6% | -8.9% | 15.6% |
| Pop. 1990 to Now | 6.9% | -16.8% | 30.8% |
| space4 | | | |
| Population Density | 301.0 | 2,526.4 | 93.4 |
| Land Area | 12.2 | 3.3 | 3,531,905.4 |
| Water Area | 16.9 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Shelter Island, NY | Hornell, NY | United States |
| Age 0 to 4 | 3.2% | 5.8% | 5.9% |
| Age 5 to 9 | 1.0% | 3.9% | 6.1% |
| Age 10 to 14 | 3.4% | 5.8% | 6.6% |
| Age 15 to 17 | 1.8% | 4.5% | 3.9% |
| Age 18 to 20 | 2.3% | 4.5% | 4.0% |
| Age 21 to 24 | 11.0% | 5.8% | 5.2% |
| Age 25 to 34 | 2.1% | 13.5% | 13.8% |
| Age 35 to 44 | 18.5% | 11.1% | 12.9% |
| Age 45 to 54 | 14.9% | 10.2% | 12.6% |
| Age 55 to 59 | 2.5% | 7.6% | 6.7% |
| Age 60 to 64 | 3.1% | 6.4% | 6.3% |
| Age 65 to 74 | 24.4% | 12.4% | 9.6% |
| Age 75 to 84 | 4.8% | 6.0% | 4.5% |
| Age 85 and over | 6.8% | 2.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Shelter Island, NY | Hornell, NY | United States |
| White | 89.3% | 90.8% | 59.4% |
| Black | 0.8% | 1.2% | 12.2% |
| Asian | 6.5% | 1.2% | 5.6% |
| Native American | 3.3% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 1.3% | 0.4% |
| Two or More Races | 0.0% | 2.5% | 3.2% |
| Hispanic | 0.0% | 3.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Shelter Island, NY | Hornell, NY | United States |
| Married Population | 40.3% | 39.0% | 49.8% |
| Currently Married | 40.3% | 36.4% | 48.0% |
| Married but Separated | 0.0% | 2.6% | 1.8% |
| Single Population | 59.7% | 61.0% | 50.2% |
| Never Married | 40.8% | 36.5% | 33.8% |
| Divorced | 18.0% | 18.5% | 10.8% |
| Widowed | 0.9% | 6.0% | 5.6% |
| space5 | | | |
| Household Size | 2.03 | 2.25 | 2.60 |
| Households | 1,783 | 3,599 | 124,010,992 |
| Family Households | 1,052 | 2,099 | 80,755,759 |
| Married couple, w/children | 13.8% | 17.8% | 30.5% |
| Married couple, no children | 52.7% | 37.0% | 42.9% |
| Non Family Households | 731 | 1,500 | 43,255,233 |
| Single householder, w/children | 5.5% | 30.0% | 15.8% |
| Single householder, no children | 28.0% | 15.3% | 10.8% |