| | Clarksville, IN | Spring Hill, FL | United States |
| Population | 21,866 | 100,270 | 321,418,820 |
| Population - 2010 | 22,947 | 96,702 | 308,745,538 |
| Population - 2000 | 21,400 | 69,078 | 285,036,114 |
| Population - 1990 | 19,833 | 31,117 | 251,960,433 |
| Pop. 1990 to Now | 10.25% | 222.24% | 27.57% |
| Pop. 2000 to Now | 2.18% | 45.16% | 12.76% |
| Pop. Density | 2,192 | 1,676 | 91 |
| Land Area | 10 | 60 | 3,531,905 |
| Water Area | 0 | 2 | 264,837 |
| Median Age | 37.5 | 45.1 | 37.4 |
| Female Population | 53.95% | 52.46% | 50.81% |
| Male Population | 46.05% | 47.54% | 49.19% |
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| EST. TOTAL POPULATION BY AGE | | | |
| | Clarksville, IN | Spring Hill, FL | United States |
| Age 0 to 4 | 8.01% | 4.91% | 6.36% |
| Age 5 to 9 | 6.07% | 6.36% | 6.51% |
| Age 10 to 14 | 6.45% | 6.01% | 6.59% |
| Age 15 to 17 | 3.13% | 4.05% | 4.03% |
| Age 18 to 20 | 4.28% | 3.22% | 4.35% |
| Age 21 to 24 | 4.69% | 3.80% | 5.61% |
| Age 25 to 34 | 15.19% | 10.10% | 13.47% |
| Age 35 to 44 | 12.36% | 11.40% | 12.97% |
| Age 45 to 54 | 13.53% | 13.77% | 14.09% |
| Age 55 to 59 | 4.93% | 6.36% | 6.57% |
| Age 60 to 64 | 5.48% | 6.92% | 5.72% |
| Age 65 to 74 | 8.63% | 12.41% | 7.64% |
| Age 75 to 84 | 4.66% | 7.63% | 4.26% |
| Age 85 and over | 2.58% | 3.07% | 1.85% |
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| RACE | | | |
| | Clarksville, IN | Spring Hill, FL | United States |
| White | 80.97% | 76.59% | 62.77% |
| Black | 5.13% | 4.63% | 12.24% |
| Asian | 0.55% | 1.32% | 4.95% |
| Native American | 0.20% | 0.20% | 0.66% |
| Hawaiian, Pacific Islander | 0.00% | 0.06% | 0.16% |
| Other | 0.05% | 0.33% | 0.20% |
| Two or More Races | 2.54% | 2.03% | 2.13% |
| Hispanic | 10.58% | 14.85% | 16.90% |
| Non-Hispanic | 89.42% | 85.15% | 83.10% |
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| FAMILY | | | |
| | Clarksville, IN | Spring Hill, FL | United States |
| Households | 8,794 | 38,703 | 116,211,000 |
| Family Households | 5,023 | 27,043 | 76,958,100 |
| Non Family Households | 3,771 | 11,660 | 39,253,000 |
| Household Size | 2.42 | 2.56 | 2.63 |
| Married Population | 44.82% | 54.67% | 50.58% |
| Single Population | 55.18% | 45.33% | 49.42% |
| Now Married | 42.85% | 52.32% | 48.41% |
| Married but Separated | 1.97% | 2.36% | 2.17% |
| Never Married | 29.58% | 23.84% | 32.55% |
| Widowed | 10.02% | 9.52% | 5.95% |
| Divorced | 15.58% | 11.97% | 10.92% |
| Married, w/children | 29.66% | 25.20% | 31.68% |
| Married, no children | 38.38% | 49.28% | 41.44% |
| Single, w/children | 20.47% | 15.14% | 16.94% |
| Single, no children | 11.49% | 10.39% | 9.95% |