| | Ortonville, MN | Willmar, MN | United States |
| Population | 2,045 | 20,823 | 329,725,481 |
| Female Population | 50.7% | 51.6% | 50.5% |
| Male Population | 49.3% | 48.4% | 49.5% |
| Median Age | 46.2 | 34.2 | 38.4 |
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| Population - 2010 | 1,922 | 19,580 | 309,327,143 |
| Population - 2000 | 2,158 | 18,351 | 285,036,114 |
| Population - 1990 | 2,205 | 17,531 | 251,960,433 |
| Pop. 2000 to Now | -19.0% | 8.4% | 15.6% |
| Pop. 1990 to Now | -20.7% | 13.5% | 30.8% |
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| Population Density | 489.9 | 1,490.4 | 93.4 |
| Land Area | 4.2 | 14.0 | 3,531,905.4 |
| Water Area | 0.7 | 1.3 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Ortonville, MN | Willmar, MN | United States |
| Age 0 to 4 | 4.1% | 7.8% | 5.9% |
| Age 5 to 9 | 6.7% | 7.5% | 6.1% |
| Age 10 to 14 | 4.7% | 7.6% | 6.6% |
| Age 15 to 17 | 2.1% | 3.4% | 3.9% |
| Age 18 to 20 | 0.6% | 4.8% | 4.0% |
| Age 21 to 24 | 6.4% | 5.6% | 5.2% |
| Age 25 to 34 | 13.8% | 14.4% | 13.8% |
| Age 35 to 44 | 9.4% | 11.5% | 12.9% |
| Age 45 to 54 | 11.4% | 9.9% | 12.6% |
| Age 55 to 59 | 4.4% | 5.7% | 6.7% |
| Age 60 to 64 | 7.8% | 5.6% | 6.3% |
| Age 65 to 74 | 12.1% | 9.2% | 9.6% |
| Age 75 to 84 | 9.2% | 3.4% | 4.5% |
| Age 85 and over | 7.4% | 3.5% | 1.9% |
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| Race | | | |
| | Ortonville, MN | Willmar, MN | United States |
| White | 93.2% | 61.6% | 59.4% |
| Black | 0.2% | 11.1% | 12.2% |
| Asian | 0.6% | 1.1% | 5.6% |
| Native American | 0.0% | 0.6% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 2.9% | 2.1% | 3.2% |
| Hispanic | 3.1% | 23.4% | 18.4% |
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| Marriage & Family | | | |
| | Ortonville, MN | Willmar, MN | United States |
| Married Population | 53.6% | 47.4% | 49.8% |
| Currently Married | 53.6% | 46.5% | 48.0% |
| Married but Separated | 0.0% | 0.9% | 1.8% |
| Single Population | 46.4% | 52.6% | 50.2% |
| Never Married | 25.0% | 37.0% | 33.8% |
| Divorced | 9.8% | 9.3% | 10.8% |
| Widowed | 11.5% | 6.3% | 5.6% |
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| Household Size | 1.97 | 2.56 | 2.60 |
| Households | 996 | 7,775 | 124,010,992 |
| Family Households | 509 | 4,857 | 80,755,759 |
| Married couple, w/children | 25.0% | 27.9% | 30.5% |
| Married couple, no children | 65.6% | 43.0% | 42.9% |
| Non Family Households | 487 | 2,918 | 43,255,233 |
| Single householder, w/children | 8.1% | 20.2% | 15.8% |
| Single householder, no children | 1.4% | 9.0% | 10.8% |