| | Elmira, NY | Sidney, NY | United States |
| Population | 26,737 | 5,538 | 329,725,481 |
| Female Population | 50.1% | 50.4% | 50.5% |
| Male Population | 49.9% | 49.6% | 49.5% |
| Median Age | 35.8 | 47.6 | 38.4 |
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| Population - 2010 | 29,258 | 5,765 | 309,327,143 |
| Population - 2000 | 30,940 | 6,109 | 285,036,114 |
| Population - 1990 | 33,724 | 6,667 | 251,960,433 |
| Pop. 2000 to Now | -12.6% | -13.5% | 15.6% |
| Pop. 1990 to Now | -19.8% | -20.7% | 30.8% |
| space4 | | | |
| Population Density | 3,686.9 | 110.9 | 93.4 |
| Land Area | 7.3 | 49.9 | 3,531,905.4 |
| Water Area | 0.3 | 0.7 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Elmira, NY | Sidney, NY | United States |
| Age 0 to 4 | 4.7% | 5.7% | 5.9% |
| Age 5 to 9 | 6.5% | 7.1% | 6.1% |
| Age 10 to 14 | 7.8% | 6.8% | 6.6% |
| Age 15 to 17 | 3.4% | 3.8% | 3.9% |
| Age 18 to 20 | 5.4% | 1.5% | 4.0% |
| Age 21 to 24 | 5.0% | 3.4% | 5.2% |
| Age 25 to 34 | 16.0% | 10.5% | 13.8% |
| Age 35 to 44 | 13.1% | 8.9% | 12.9% |
| Age 45 to 54 | 11.4% | 10.9% | 12.6% |
| Age 55 to 59 | 7.1% | 7.9% | 6.7% |
| Age 60 to 64 | 5.4% | 8.5% | 6.3% |
| Age 65 to 74 | 9.2% | 13.7% | 9.6% |
| Age 75 to 84 | 2.8% | 7.2% | 4.5% |
| Age 85 and over | 2.1% | 4.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Elmira, NY | Sidney, NY | United States |
| White | 74.9% | 93.4% | 59.4% |
| Black | 11.7% | 1.5% | 12.2% |
| Asian | 1.0% | 0.3% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.6% | 0.0% | 0.4% |
| Two or More Races | 6.0% | 3.5% | 3.2% |
| Hispanic | 5.6% | 1.4% | 18.4% |
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| Marriage & Family | | | |
| | Elmira, NY | Sidney, NY | United States |
| Married Population | 37.2% | 49.2% | 49.8% |
| Currently Married | 33.9% | 46.6% | 48.0% |
| Married but Separated | 3.3% | 2.7% | 1.8% |
| Single Population | 62.8% | 50.8% | 50.2% |
| Never Married | 44.5% | 26.3% | 33.8% |
| Divorced | 13.1% | 13.3% | 10.8% |
| Widowed | 5.1% | 11.2% | 5.6% |
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| Household Size | 2.36 | 2.45 | 2.60 |
| Households | 9,871 | 2,240 | 124,010,992 |
| Family Households | 5,603 | 1,423 | 80,755,759 |
| Married couple, w/children | 24.8% | 14.8% | 30.5% |
| Married couple, no children | 33.0% | 53.1% | 42.9% |
| Non Family Households | 4,268 | 817 | 43,255,233 |
| Single householder, w/children | 29.6% | 20.8% | 15.8% |
| Single householder, no children | 12.6% | 11.3% | 10.8% |