| | Siloam Springs, AR | Leach, OK | United States |
| Population | 16,944 | 322 | 329,725,481 |
| Female Population | 51.3% | 46.9% | 50.5% |
| Male Population | 48.7% | 53.1% | 49.5% |
| Median Age | 30.7 | 36.8 | 38.4 |
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| Population - 2010 | 15,166 | 200 | 309,327,143 |
| Population - 2000 | 10,843 | 220 | 285,036,114 |
| Population - 1990 | 8,151 | 208 | 251,960,433 |
| Pop. 2000 to Now | 62.4% | 36.8% | 15.6% |
| Pop. 1990 to Now | 116.1% | 44.7% | 30.8% |
| space4 | | | |
| Population Density | 1,489.2 | 56.0 | 93.4 |
| Land Area | 11.4 | 5.8 | 3,531,905.4 |
| Water Area | 0.2 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Siloam Springs, AR | Leach, OK | United States |
| Age 0 to 4 | 9.3% | 5.3% | 5.9% |
| Age 5 to 9 | 7.6% | 8.4% | 6.1% |
| Age 10 to 14 | 6.4% | 9.9% | 6.6% |
| Age 15 to 17 | 4.0% | 4.7% | 3.9% |
| Age 18 to 20 | 7.0% | 4.3% | 4.0% |
| Age 21 to 24 | 6.6% | 1.2% | 5.2% |
| Age 25 to 34 | 16.5% | 14.6% | 13.8% |
| Age 35 to 44 | 9.4% | 16.1% | 12.9% |
| Age 45 to 54 | 8.5% | 8.4% | 12.6% |
| Age 55 to 59 | 7.5% | 4.7% | 6.7% |
| Age 60 to 64 | 7.1% | 5.6% | 6.3% |
| Age 65 to 74 | 5.7% | 14.6% | 9.6% |
| Age 75 to 84 | 3.3% | 1.9% | 4.5% |
| Age 85 and over | 1.2% | 0.3% | 1.9% |
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| Race | | | |
| | Siloam Springs, AR | Leach, OK | United States |
| White | 58.4% | 34.5% | 59.4% |
| Black | 1.1% | 0.0% | 12.2% |
| Asian | 3.2% | 2.8% | 5.6% |
| Native American | 6.1% | 49.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.4% | 0.0% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 10.1% | 13.4% | 3.2% |
| Hispanic | 20.8% | 0.0% | 18.4% |
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| Marriage & Family | | | |
| | Siloam Springs, AR | Leach, OK | United States |
| Married Population | 51.5% | 59.4% | 49.8% |
| Currently Married | 50.6% | 57.7% | 48.0% |
| Married but Separated | 1.0% | 1.6% | 1.8% |
| Single Population | 48.5% | 40.7% | 50.2% |
| Never Married | 33.7% | 24.8% | 33.8% |
| Divorced | 9.5% | 11.8% | 10.8% |
| Widowed | 5.2% | 4.1% | 5.6% |
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| Household Size | 2.68 | 2.66 | 2.60 |
| Households | 5,917 | 121 | 124,010,992 |
| Family Households | 4,365 | 76 | 80,755,759 |
| Married couple, w/children | 34.8% | 57.9% | 30.5% |
| Married couple, no children | 41.3% | 36.8% | 42.9% |
| Non Family Households | 1,552 | 45 | 43,255,233 |
| Single householder, w/children | 19.7% | 0.0% | 15.8% |
| Single householder, no children | 4.2% | 5.3% | 10.8% |