| | Onalaska, WI | Iola, KS | United States |
| Population | 18,760 | 5,378 | 329,725,481 |
| Female Population | 53.1% | 51.5% | 50.5% |
| Male Population | 46.9% | 48.6% | 49.5% |
| Median Age | 39.6 | 36 | 38.4 |
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| Population - 2010 | 17,810 | 5,702 | 309,327,143 |
| Population - 2000 | 14,839 | 6,302 | 285,036,114 |
| Population - 1990 | 11,284 | 6,351 | 251,960,433 |
| Pop. 2000 to Now | 28.8% | -16.5% | 15.6% |
| Pop. 1990 to Now | 69.3% | -17.1% | 30.8% |
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| Population Density | 1,832.6 | 1,202.3 | 93.4 |
| Land Area | 10.2 | 4.5 | 3,531,905.4 |
| Water Area | 0.6 | 0.3 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Onalaska, WI | Iola, KS | United States |
| Age 0 to 4 | 4.6% | 4.8% | 5.9% |
| Age 5 to 9 | 5.2% | 8.4% | 6.1% |
| Age 10 to 14 | 6.7% | 6.3% | 6.6% |
| Age 15 to 17 | 4.6% | 3.1% | 3.9% |
| Age 18 to 20 | 2.3% | 6.2% | 4.0% |
| Age 21 to 24 | 7.1% | 7.1% | 5.2% |
| Age 25 to 34 | 13.2% | 13.4% | 13.8% |
| Age 35 to 44 | 12.2% | 9.9% | 12.9% |
| Age 45 to 54 | 11.7% | 10.8% | 12.6% |
| Age 55 to 59 | 5.9% | 7.4% | 6.7% |
| Age 60 to 64 | 7.1% | 3.8% | 6.3% |
| Age 65 to 74 | 10.4% | 8.1% | 9.6% |
| Age 75 to 84 | 4.8% | 6.5% | 4.5% |
| Age 85 and over | 4.2% | 4.2% | 1.9% |
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| Race | | | |
| | Onalaska, WI | Iola, KS | United States |
| White | 85.8% | 85.3% | 59.4% |
| Black | 2.5% | 4.5% | 12.2% |
| Asian | 6.7% | 1.0% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.9% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.9% | 3.4% | 3.2% |
| Hispanic | 1.9% | 4.8% | 18.4% |
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| Marriage & Family | | | |
| | Onalaska, WI | Iola, KS | United States |
| Married Population | 51.7% | 45.3% | 49.8% |
| Currently Married | 50.8% | 42.6% | 48.0% |
| Married but Separated | 0.9% | 2.7% | 1.8% |
| Single Population | 48.3% | 54.7% | 50.2% |
| Never Married | 31.2% | 30.1% | 33.8% |
| Divorced | 8.9% | 17.0% | 10.8% |
| Widowed | 8.2% | 7.7% | 5.6% |
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| Household Size | 2.23 | 2.35 | 2.60 |
| Households | 8,389 | 2,156 | 124,010,992 |
| Family Households | 4,868 | 1,224 | 80,755,759 |
| Married couple, w/children | 29.2% | 19.6% | 30.5% |
| Married couple, no children | 51.8% | 42.6% | 42.9% |
| Non Family Households | 3,521 | 932 | 43,255,233 |
| Single householder, w/children | 15.1% | 25.0% | 15.8% |
| Single householder, no children | 3.8% | 12.7% | 10.8% |