| | Hartsdale, NY | West Seneca, NY | United States |
| Population | 2,964 | 45,390 | 329,725,481 |
| Female Population | 59.4% | 52.2% | 50.5% |
| Male Population | 40.6% | 47.8% | 49.5% |
| Median Age | 47.3 | 45.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 5,165 | 44,719 | 309,327,143 |
| Population - 2000 | 9,830 | 45,943 | 285,036,114 |
| Population - 1990 | 9,587 | 47,866 | 251,960,433 |
| Pop. 2000 to Now | -48.1% | -1.7% | 15.6% |
| Pop. 1990 to Now | -46.8% | -5.7% | 30.8% |
| space4 | | | |
| Population Density | 3,311.7 | 2,122.3 | 93.4 |
| Land Area | 0.9 | 21.4 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Hartsdale, NY | West Seneca, NY | United States |
| Age 0 to 4 | 5.7% | 4.6% | 5.9% |
| Age 5 to 9 | 5.4% | 4.5% | 6.1% |
| Age 10 to 14 | 2.8% | 4.8% | 6.6% |
| Age 15 to 17 | 1.4% | 4.2% | 3.9% |
| Age 18 to 20 | 0.4% | 3.1% | 4.0% |
| Age 21 to 24 | 3.5% | 4.6% | 5.2% |
| Age 25 to 34 | 6.2% | 13.8% | 13.8% |
| Age 35 to 44 | 19.6% | 10.1% | 12.9% |
| Age 45 to 54 | 15.7% | 14.5% | 12.6% |
| Age 55 to 59 | 7.5% | 8.3% | 6.7% |
| Age 60 to 64 | 9.5% | 7.1% | 6.3% |
| Age 65 to 74 | 10.4% | 11.5% | 9.6% |
| Age 75 to 84 | 7.2% | 6.3% | 4.5% |
| Age 85 and over | 4.7% | 2.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Hartsdale, NY | West Seneca, NY | United States |
| White | 64.6% | 93.9% | 59.4% |
| Black | 2.5% | 1.5% | 12.2% |
| Asian | 16.1% | 0.3% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 4.6% | 1.2% | 3.2% |
| Hispanic | 12.2% | 3.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Hartsdale, NY | West Seneca, NY | United States |
| Married Population | 62.5% | 46.8% | 49.8% |
| Currently Married | 59.3% | 45.8% | 48.0% |
| Married but Separated | 3.2% | 1.1% | 1.8% |
| Single Population | 37.5% | 53.2% | 50.2% |
| Never Married | 23.5% | 35.3% | 33.8% |
| Divorced | 7.1% | 9.5% | 10.8% |
| Widowed | 6.9% | 8.4% | 5.6% |
| space5 | | | |
| Household Size | 2.13 | 2.26 | 2.60 |
| Households | 1,351 | 19,863 | 124,010,992 |
| Family Households | 871 | 11,783 | 80,755,759 |
| Married couple, w/children | 31.0% | 27.1% | 30.5% |
| Married couple, no children | 50.7% | 46.3% | 42.9% |
| Non Family Households | 480 | 8,080 | 43,255,233 |
| Single householder, w/children | 4.5% | 13.7% | 15.8% |
| Single householder, no children | 13.8% | 12.9% | 10.8% |