| | Wauwatosa, WI | Westerville, OH | United States |
| Population | 48,072 | 38,960 | 329,725,481 |
| Female Population | 52.6% | 52.5% | 50.5% |
| Male Population | 47.4% | 47.6% | 49.5% |
| Median Age | 38.4 | 40.6 | 38.4 |
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| Population - 2010 | 46,436 | 36,483 | 309,327,143 |
| Population - 2000 | 47,271 | 35,318 | 285,036,114 |
| Population - 1990 | 49,366 | 30,269 | 251,960,433 |
| Pop. 2000 to Now | 1.7% | 17.4% | 15.6% |
| Pop. 1990 to Now | -2.6% | 37.0% | 30.8% |
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| Population Density | 3,634.4 | 3,091.3 | 93.4 |
| Land Area | 13.2 | 12.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Wauwatosa, WI | Westerville, OH | United States |
| Age 0 to 4 | 6.1% | 6.6% | 5.9% |
| Age 5 to 9 | 6.4% | 6.5% | 6.1% |
| Age 10 to 14 | 5.6% | 6.2% | 6.6% |
| Age 15 to 17 | 4.1% | 3.1% | 3.9% |
| Age 18 to 20 | 2.4% | 5.0% | 4.0% |
| Age 21 to 24 | 3.3% | 3.7% | 5.2% |
| Age 25 to 34 | 16.8% | 11.2% | 13.8% |
| Age 35 to 44 | 14.1% | 13.5% | 12.9% |
| Age 45 to 54 | 12.3% | 11.8% | 12.6% |
| Age 55 to 59 | 6.1% | 5.7% | 6.7% |
| Age 60 to 64 | 5.6% | 6.4% | 6.3% |
| Age 65 to 74 | 9.4% | 13.1% | 9.6% |
| Age 75 to 84 | 4.1% | 5.2% | 4.5% |
| Age 85 and over | 3.7% | 2.0% | 1.9% |
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| Race | | | |
| | Wauwatosa, WI | Westerville, OH | United States |
| White | 80.5% | 85.2% | 59.4% |
| Black | 7.0% | 6.1% | 12.2% |
| Asian | 4.5% | 2.4% | 5.6% |
| Native American | 0.4% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.0% | 0.4% |
| Two or More Races | 3.9% | 4.6% | 3.2% |
| Hispanic | 3.4% | 1.7% | 18.4% |
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| Marriage & Family | | | |
| | Wauwatosa, WI | Westerville, OH | United States |
| Married Population | 51.3% | 60.3% | 49.8% |
| Currently Married | 49.9% | 59.7% | 48.0% |
| Married but Separated | 1.4% | 0.6% | 1.8% |
| Single Population | 48.7% | 39.7% | 50.2% |
| Never Married | 33.3% | 24.8% | 33.8% |
| Divorced | 9.8% | 9.8% | 10.8% |
| Widowed | 5.6% | 5.1% | 5.6% |
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| Household Size | 2.27 | 2.50 | 2.60 |
| Households | 20,895 | 14,797 | 124,010,992 |
| Family Households | 12,205 | 10,683 | 80,755,759 |
| Married couple, w/children | 35.5% | 37.4% | 30.5% |
| Married couple, no children | 42.9% | 46.3% | 42.9% |
| Non Family Households | 8,690 | 4,114 | 43,255,233 |
| Single householder, w/children | 14.3% | 10.0% | 15.8% |
| Single householder, no children | 7.3% | 6.3% | 10.8% |