| | New Hampton, IA | Oelwein, IA | United States |
| Population | 3,452 | 5,961 | 329,725,481 |
| Female Population | 50.5% | 51.3% | 50.5% |
| Male Population | 49.5% | 48.7% | 49.5% |
| Median Age | 41.8 | 43.2 | 38.4 |
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| Population - 2010 | 3,560 | 6,406 | 309,327,143 |
| Population - 2000 | 3,692 | 6,692 | 285,036,114 |
| Population - 1990 | 3,660 | 6,493 | 251,960,433 |
| Pop. 2000 to Now | -8.4% | -13.5% | 15.6% |
| Pop. 1990 to Now | -7.6% | -10.8% | 30.8% |
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| Population Density | 1,093.1 | 1,232.9 | 93.4 |
| Land Area | 3.2 | 4.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | New Hampton, IA | Oelwein, IA | United States |
| Age 0 to 4 | 9.2% | 4.8% | 5.9% |
| Age 5 to 9 | 8.6% | 7.5% | 6.1% |
| Age 10 to 14 | 4.5% | 6.7% | 6.6% |
| Age 15 to 17 | 4.0% | 3.9% | 3.9% |
| Age 18 to 20 | 2.8% | 3.7% | 4.0% |
| Age 21 to 24 | 6.5% | 2.6% | 5.2% |
| Age 25 to 34 | 9.8% | 11.4% | 13.8% |
| Age 35 to 44 | 7.5% | 12.4% | 12.9% |
| Age 45 to 54 | 13.3% | 12.2% | 12.6% |
| Age 55 to 59 | 4.3% | 8.3% | 6.7% |
| Age 60 to 64 | 10.1% | 5.7% | 6.3% |
| Age 65 to 74 | 11.4% | 11.9% | 9.6% |
| Age 75 to 84 | 5.4% | 5.9% | 4.5% |
| Age 85 and over | 2.5% | 3.1% | 1.9% |
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| Race | | | |
| | New Hampton, IA | Oelwein, IA | United States |
| White | 90.3% | 91.7% | 59.4% |
| Black | 1.0% | 1.5% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 0.3% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.0% | 4.2% | 3.2% |
| Hispanic | 8.4% | 2.5% | 18.4% |
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| Marriage & Family | | | |
| | New Hampton, IA | Oelwein, IA | United States |
| Married Population | 58.8% | 41.5% | 49.8% |
| Currently Married | 58.5% | 39.1% | 48.0% |
| Married but Separated | 0.3% | 2.5% | 1.8% |
| Single Population | 41.2% | 58.5% | 50.2% |
| Never Married | 22.4% | 31.1% | 33.8% |
| Divorced | 11.9% | 17.8% | 10.8% |
| Widowed | 6.9% | 9.7% | 5.6% |
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| Household Size | 2.27 | 2.34 | 2.60 |
| Households | 1,466 | 2,494 | 124,010,992 |
| Family Households | 884 | 1,314 | 80,755,759 |
| Married couple, w/children | 37.1% | 27.2% | 30.5% |
| Married couple, no children | 43.8% | 41.4% | 42.9% |
| Non Family Households | 582 | 1,180 | 43,255,233 |
| Single householder, w/children | 14.5% | 21.2% | 15.8% |
| Single householder, no children | 4.6% | 10.2% | 10.8% |