| | Hill City, SD | Clayton, OK | United States |
| Population | 626 | 639 | 329,725,481 |
| Female Population | 42.8% | 46.3% | 50.5% |
| Male Population | 57.2% | 53.7% | 49.5% |
| Median Age | 41.3 | 35.4 | 38.4 |
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| Population - 2010 | 964 | 824 | 309,327,143 |
| Population - 2000 | 780 | 719 | 285,036,114 |
| Population - 1990 | 650 | 636 | 251,960,433 |
| Pop. 2000 to Now | 37.7% | 7.9% | 15.6% |
| Pop. 1990 to Now | 65.2% | 22.0% | 30.8% |
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| Population Density | 498.0 | 372.2 | 93.4 |
| Land Area | 1.3 | 1.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Hill City, SD | Clayton, OK | United States |
| Age 0 to 4 | 6.2% | 9.5% | 5.9% |
| Age 5 to 9 | 5.4% | 4.9% | 6.1% |
| Age 10 to 14 | 6.9% | 3.0% | 6.6% |
| Age 15 to 17 | 7.8% | 6.1% | 3.9% |
| Age 18 to 20 | 8.3% | 5.6% | 4.0% |
| Age 21 to 24 | 2.6% | 2.0% | 5.2% |
| Age 25 to 34 | 9.4% | 18.2% | 13.8% |
| Age 35 to 44 | 11.3% | 8.8% | 12.9% |
| Age 45 to 54 | 11.5% | 10.3% | 12.6% |
| Age 55 to 59 | 6.2% | 5.9% | 6.7% |
| Age 60 to 64 | 8.9% | 5.0% | 6.3% |
| Age 65 to 74 | 12.1% | 13.0% | 9.6% |
| Age 75 to 84 | 1.4% | 7.0% | 4.5% |
| Age 85 and over | 1.8% | 0.6% | 1.9% |
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| Race | | | |
| | Hill City, SD | Clayton, OK | United States |
| White | 70.9% | 56.3% | 59.4% |
| Black | 0.0% | 1.6% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 0.5% | 18.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 1.1% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 15.2% | 19.1% | 3.2% |
| Hispanic | 13.4% | 3.9% | 18.4% |
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| Marriage & Family | | | |
| | Hill City, SD | Clayton, OK | United States |
| Married Population | 49.2% | 35.4% | 49.8% |
| Currently Married | 49.2% | 31.1% | 48.0% |
| Married but Separated | 0.0% | 4.4% | 1.8% |
| Single Population | 50.8% | 64.6% | 50.2% |
| Never Married | 32.4% | 33.3% | 33.8% |
| Divorced | 15.3% | 23.3% | 10.8% |
| Widowed | 3.1% | 8.0% | 5.6% |
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| Household Size | 2.95 | 2.27 | 2.60 |
| Households | 209 | 282 | 124,010,992 |
| Family Households | 149 | 119 | 80,755,759 |
| Married couple, w/children | 36.2% | 24.4% | 30.5% |
| Married couple, no children | 43.0% | 31.9% | 42.9% |
| Non Family Households | 60 | 163 | 43,255,233 |
| Single householder, w/children | 18.8% | 32.8% | 15.8% |
| Single householder, no children | 2.0% | 10.9% | 10.8% |