| | Monticello, IA | Milwaukee, WI | United States |
| Population | 3,994 | 578,198 | 329,725,481 |
| Female Population | 52.2% | 51.5% | 50.5% |
| Male Population | 47.8% | 48.5% | 49.5% |
| Median Age | 38.4 | 31.6 | 38.4 |
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| Population - 2010 | 3,785 | 594,883 | 309,327,143 |
| Population - 2000 | 3,607 | 596,974 | 285,036,114 |
| Population - 1990 | 3,522 | 628,088 | 251,960,433 |
| Pop. 2000 to Now | 7.4% | -1.3% | 15.6% |
| Pop. 1990 to Now | 10.0% | -6.2% | 30.8% |
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| Population Density | 718.6 | 6,011.3 | 93.4 |
| Land Area | 5.6 | 96.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.6 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Monticello, IA | Milwaukee, WI | United States |
| Age 0 to 4 | 9.8% | 7.5% | 5.9% |
| Age 5 to 9 | 4.4% | 7.2% | 6.1% |
| Age 10 to 14 | 6.7% | 7.6% | 6.6% |
| Age 15 to 17 | 5.1% | 4.0% | 3.9% |
| Age 18 to 20 | 2.2% | 5.3% | 4.0% |
| Age 21 to 24 | 5.5% | 6.4% | 5.2% |
| Age 25 to 34 | 12.0% | 17.0% | 13.8% |
| Age 35 to 44 | 12.0% | 12.8% | 12.9% |
| Age 45 to 54 | 7.2% | 10.9% | 12.6% |
| Age 55 to 59 | 9.4% | 5.4% | 6.7% |
| Age 60 to 64 | 6.4% | 5.1% | 6.3% |
| Age 65 to 74 | 8.6% | 6.7% | 9.6% |
| Age 75 to 84 | 7.2% | 2.7% | 4.5% |
| Age 85 and over | 3.6% | 1.4% | 1.9% |
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| Race | | | |
| | Monticello, IA | Milwaukee, WI | United States |
| White | 89.0% | 33.0% | 59.4% |
| Black | 1.3% | 38.9% | 12.2% |
| Asian | 0.3% | 4.4% | 5.6% |
| Native American | 0.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 3.8% | 3.2% | 3.2% |
| Hispanic | 5.6% | 19.9% | 18.4% |
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| Marriage & Family | | | |
| | Monticello, IA | Milwaukee, WI | United States |
| Married Population | 48.8% | 31.3% | 49.8% |
| Currently Married | 47.4% | 29.4% | 48.0% |
| Married but Separated | 1.4% | 1.9% | 1.8% |
| Single Population | 51.3% | 68.7% | 50.2% |
| Never Married | 33.1% | 54.4% | 33.8% |
| Divorced | 10.9% | 9.9% | 10.8% |
| Widowed | 7.3% | 4.4% | 5.6% |
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| Household Size | 2.28 | 2.45 | 2.60 |
| Households | 1,709 | 229,470 | 124,010,992 |
| Family Households | 932 | 120,856 | 80,755,759 |
| Married couple, w/children | 33.7% | 22.0% | 30.5% |
| Married couple, no children | 45.0% | 27.1% | 42.9% |
| Non Family Households | 777 | 108,614 | 43,255,233 |
| Single householder, w/children | 14.6% | 34.4% | 15.8% |
| Single householder, no children | 6.8% | 16.5% | 10.8% |