| | Mendon, NY | Erie, PA | United States |
| Population | 9,126 | 95,536 | 329,725,481 |
| Female Population | 50.6% | 50.8% | 50.5% |
| Male Population | 49.4% | 49.2% | 49.5% |
| Median Age | 46.2 | 35.1 | 38.4 |
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| Population - 2010 | 9,145 | 101,719 | 309,327,143 |
| Population - 2000 | 8,370 | 103,717 | 285,036,114 |
| Population - 1990 | 6,845 | 108,718 | 251,960,433 |
| Pop. 2000 to Now | 10.8% | -8.3% | 15.6% |
| Pop. 1990 to Now | 35.5% | -12.6% | 30.8% |
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| Population Density | 231.2 | 4,992.0 | 93.4 |
| Land Area | 39.5 | 19.1 | 3,531,905.4 |
| Water Area | 0.5 | 0.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Mendon, NY | Erie, PA | United States |
| Age 0 to 4 | 6.8% | 6.4% | 5.9% |
| Age 5 to 9 | 6.4% | 5.8% | 6.1% |
| Age 10 to 14 | 4.9% | 6.2% | 6.6% |
| Age 15 to 17 | 5.7% | 3.9% | 3.9% |
| Age 18 to 20 | 3.0% | 5.5% | 4.0% |
| Age 21 to 24 | 4.0% | 6.6% | 5.2% |
| Age 25 to 34 | 7.0% | 15.5% | 13.8% |
| Age 35 to 44 | 11.1% | 10.9% | 12.9% |
| Age 45 to 54 | 18.6% | 11.3% | 12.6% |
| Age 55 to 59 | 9.1% | 6.4% | 6.7% |
| Age 60 to 64 | 7.0% | 6.6% | 6.3% |
| Age 65 to 74 | 8.3% | 8.9% | 9.6% |
| Age 75 to 84 | 6.2% | 3.9% | 4.5% |
| Age 85 and over | 2.1% | 2.2% | 1.9% |
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| Race | | | |
| | Mendon, NY | Erie, PA | United States |
| White | 91.5% | 68.0% | 59.4% |
| Black | 1.4% | 15.2% | 12.2% |
| Asian | 1.0% | 2.8% | 5.6% |
| Native American | 0.0% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.6% | 0.4% |
| Two or More Races | 3.6% | 5.0% | 3.2% |
| Hispanic | 2.6% | 8.1% | 18.4% |
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| Marriage & Family | | | |
| | Mendon, NY | Erie, PA | United States |
| Married Population | 64.4% | 35.4% | 49.8% |
| Currently Married | 63.3% | 32.7% | 48.0% |
| Married but Separated | 1.1% | 2.7% | 1.8% |
| Single Population | 35.6% | 64.6% | 50.2% |
| Never Married | 22.5% | 46.3% | 33.8% |
| Divorced | 8.2% | 12.4% | 10.8% |
| Widowed | 4.8% | 5.9% | 5.6% |
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| Household Size | 2.62 | 2.31 | 2.60 |
| Households | 3,470 | 38,992 | 124,010,992 |
| Family Households | 2,573 | 20,395 | 80,755,759 |
| Married couple, w/children | 39.2% | 20.7% | 30.5% |
| Married couple, no children | 49.0% | 36.3% | 42.9% |
| Non Family Households | 897 | 18,597 | 43,255,233 |
| Single householder, w/children | 9.1% | 30.4% | 15.8% |
| Single householder, no children | 2.6% | 12.5% | 10.8% |