| | Spencer, IN | Ellettsville, IN | United States |
| Population | 2,149 | 6,559 | 329,725,481 |
| Female Population | 54.1% | 54.0% | 50.5% |
| Male Population | 45.9% | 46.0% | 49.5% |
| Median Age | 46.3 | 36 | 38.4 |
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| Population - 2010 | 2,363 | 6,233 | 309,327,143 |
| Population - 2000 | 2,508 | 5,078 | 285,036,114 |
| Population - 1990 | 2,609 | 3,275 | 251,960,433 |
| Pop. 2000 to Now | -9.8% | 32.1% | 15.6% |
| Pop. 1990 to Now | -13.3% | 104.8% | 30.8% |
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| Population Density | 1,355.8 | 1,346.3 | 93.4 |
| Land Area | 1.6 | 4.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Spencer, IN | Ellettsville, IN | United States |
| Age 0 to 4 | 8.2% | 6.0% | 5.9% |
| Age 5 to 9 | 3.5% | 7.8% | 6.1% |
| Age 10 to 14 | 3.2% | 7.0% | 6.6% |
| Age 15 to 17 | 3.7% | 2.7% | 3.9% |
| Age 18 to 20 | 3.5% | 2.5% | 4.0% |
| Age 21 to 24 | 4.7% | 4.1% | 5.2% |
| Age 25 to 34 | 11.7% | 17.8% | 13.8% |
| Age 35 to 44 | 9.5% | 16.8% | 12.9% |
| Age 45 to 54 | 9.9% | 10.2% | 12.6% |
| Age 55 to 59 | 4.3% | 6.1% | 6.7% |
| Age 60 to 64 | 10.7% | 3.3% | 6.3% |
| Age 65 to 74 | 17.6% | 7.2% | 9.6% |
| Age 75 to 84 | 5.4% | 7.8% | 4.5% |
| Age 85 and over | 4.1% | 0.7% | 1.9% |
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| Race | | | |
| | Spencer, IN | Ellettsville, IN | United States |
| White | 90.6% | 94.8% | 59.4% |
| Black | 0.0% | 1.1% | 12.2% |
| Asian | 1.3% | 0.5% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.9% | 0.0% | 0.4% |
| Two or More Races | 2.9% | 3.3% | 3.2% |
| Hispanic | 4.2% | 0.3% | 18.4% |
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| Marriage & Family | | | |
| | Spencer, IN | Ellettsville, IN | United States |
| Married Population | 41.4% | 60.6% | 49.8% |
| Currently Married | 39.8% | 60.4% | 48.0% |
| Married but Separated | 1.6% | 0.2% | 1.8% |
| Single Population | 58.6% | 39.4% | 50.2% |
| Never Married | 24.0% | 20.7% | 33.8% |
| Divorced | 22.8% | 13.8% | 10.8% |
| Widowed | 11.8% | 4.9% | 5.6% |
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| Household Size | 2.00 | 2.35 | 2.60 |
| Households | 1,049 | 2,759 | 124,010,992 |
| Family Households | 437 | 2,011 | 80,755,759 |
| Married couple, w/children | 27.5% | 35.7% | 30.5% |
| Married couple, no children | 49.0% | 41.0% | 42.9% |
| Non Family Households | 612 | 748 | 43,255,233 |
| Single householder, w/children | 13.7% | 15.7% | 15.8% |
| Single householder, no children | 9.8% | 7.6% | 10.8% |