| | Indianapolis, IN | Gary, IN | United States |
| Population | 880,104 | 69,739 | 329,725,481 |
| Female Population | 51.5% | 54.2% | 50.5% |
| Male Population | 48.5% | 45.8% | 49.5% |
| Median Age | 34.3 | 37.1 | 38.4 |
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| Population - 2010 | 821,576 | 80,159 | 309,327,143 |
| Population - 2000 | 781,870 | 102,746 | 285,036,114 |
| Population - 1990 | 754,005 | 116,646 | 251,960,433 |
| Pop. 2000 to Now | 12.3% | -27.3% | 15.6% |
| Pop. 1990 to Now | 16.4% | -36.0% | 30.8% |
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| Population Density | 2,434.0 | 1,402.7 | 93.4 |
| Land Area | 361.6 | 49.7 | 3,531,905.4 |
| Water Area | 6.5 | 7.5 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Indianapolis, IN | Gary, IN | United States |
| Age 0 to 4 | 7.1% | 7.1% | 5.9% |
| Age 5 to 9 | 6.8% | 7.8% | 6.1% |
| Age 10 to 14 | 6.9% | 7.8% | 6.6% |
| Age 15 to 17 | 3.9% | 4.5% | 3.9% |
| Age 18 to 20 | 3.9% | 3.9% | 4.0% |
| Age 21 to 24 | 5.6% | 4.4% | 5.2% |
| Age 25 to 34 | 16.8% | 11.6% | 13.8% |
| Age 35 to 44 | 13.0% | 11.7% | 12.9% |
| Age 45 to 54 | 11.6% | 10.2% | 12.6% |
| Age 55 to 59 | 6.1% | 6.1% | 6.7% |
| Age 60 to 64 | 5.8% | 6.3% | 6.3% |
| Age 65 to 74 | 7.7% | 11.5% | 9.6% |
| Age 75 to 84 | 3.3% | 4.9% | 4.5% |
| Age 85 and over | 1.5% | 2.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Indianapolis, IN | Gary, IN | United States |
| White | 52.7% | 9.9% | 59.4% |
| Black | 28.5% | 77.9% | 12.2% |
| Asian | 3.8% | 0.3% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.5% | 0.4% | 0.4% |
| Two or More Races | 3.7% | 2.8% | 3.2% |
| Hispanic | 10.8% | 8.6% | 18.4% |
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| Marriage & Family | | | |
| | Indianapolis, IN | Gary, IN | United States |
| Married Population | 41.1% | 29.6% | 49.8% |
| Currently Married | 39.4% | 26.0% | 48.0% |
| Married but Separated | 1.7% | 3.5% | 1.8% |
| Single Population | 58.9% | 70.4% | 50.2% |
| Never Married | 41.8% | 46.7% | 33.8% |
| Divorced | 12.3% | 15.0% | 10.8% |
| Widowed | 4.8% | 8.7% | 5.6% |
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| Household Size | 2.46 | 2.49 | 2.60 |
| Households | 352,238 | 27,773 | 124,010,992 |
| Family Households | 193,246 | 16,519 | 80,755,759 |
| Married couple, w/children | 26.6% | 10.4% | 30.5% |
| Married couple, no children | 38.7% | 26.8% | 42.9% |
| Non Family Households | 158,992 | 11,254 | 43,255,233 |
| Single householder, w/children | 22.4% | 41.2% | 15.8% |
| Single householder, no children | 12.4% | 21.6% | 10.8% |