| | Knox, IN | Crawfordsville, IN | United States |
| Population | 3,691 | 16,279 | 329,725,481 |
| Female Population | 51.2% | 48.6% | 50.5% |
| Male Population | 48.8% | 51.4% | 49.5% |
| Median Age | 41.4 | 36.1 | 38.4 |
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| Population - 2010 | 3,700 | 15,955 | 309,327,143 |
| Population - 2000 | 3,721 | 15,243 | 285,036,114 |
| Population - 1990 | 3,705 | 13,584 | 251,960,433 |
| Pop. 2000 to Now | -4.5% | 6.0% | 15.6% |
| Pop. 1990 to Now | -4.1% | 18.9% | 30.8% |
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| Population Density | 941.6 | 1,683.5 | 93.4 |
| Land Area | 3.9 | 9.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Knox, IN | Crawfordsville, IN | United States |
| Age 0 to 4 | 5.5% | 7.3% | 5.9% |
| Age 5 to 9 | 8.2% | 7.0% | 6.1% |
| Age 10 to 14 | 8.4% | 5.5% | 6.6% |
| Age 15 to 17 | 4.4% | 3.5% | 3.9% |
| Age 18 to 20 | 4.0% | 7.1% | 4.0% |
| Age 21 to 24 | 3.0% | 4.7% | 5.2% |
| Age 25 to 34 | 9.6% | 13.6% | 13.8% |
| Age 35 to 44 | 12.4% | 11.3% | 12.9% |
| Age 45 to 54 | 18.2% | 10.4% | 12.6% |
| Age 55 to 59 | 6.3% | 5.8% | 6.7% |
| Age 60 to 64 | 4.5% | 6.5% | 6.3% |
| Age 65 to 74 | 10.5% | 8.8% | 9.6% |
| Age 75 to 84 | 2.9% | 6.3% | 4.5% |
| Age 85 and over | 2.1% | 2.3% | 1.9% |
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| Race | | | |
| | Knox, IN | Crawfordsville, IN | United States |
| White | 89.9% | 85.9% | 59.4% |
| Black | 0.1% | 1.7% | 12.2% |
| Asian | 0.3% | 0.9% | 5.6% |
| Native American | 0.5% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.4% | 0.4% |
| Two or More Races | 4.2% | 3.0% | 3.2% |
| Hispanic | 5.0% | 8.0% | 18.4% |
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| Marriage & Family | | | |
| | Knox, IN | Crawfordsville, IN | United States |
| Married Population | 44.7% | 44.2% | 49.8% |
| Currently Married | 43.0% | 41.8% | 48.0% |
| Married but Separated | 1.7% | 2.4% | 1.8% |
| Single Population | 55.3% | 55.8% | 50.2% |
| Never Married | 24.5% | 33.1% | 33.8% |
| Divorced | 24.2% | 13.9% | 10.8% |
| Widowed | 6.6% | 8.9% | 5.6% |
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| Household Size | 2.67 | 2.25 | 2.60 |
| Households | 1,373 | 6,687 | 124,010,992 |
| Family Households | 807 | 3,620 | 80,755,759 |
| Married couple, w/children | 32.8% | 29.6% | 30.5% |
| Married couple, no children | 38.9% | 41.2% | 42.9% |
| Non Family Households | 566 | 3,067 | 43,255,233 |
| Single householder, w/children | 20.2% | 21.9% | 15.8% |
| Single householder, no children | 8.1% | 7.2% | 10.8% |