| | Cedar Falls, IA | Janesville, WI | United States |
| Population | 40,500 | 65,506 | 329,725,481 |
| Female Population | 52.8% | 51.1% | 50.5% |
| Male Population | 47.2% | 48.9% | 49.5% |
| Median Age | 28 | 39.7 | 38.4 |
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| Population - 2010 | 39,354 | 63,632 | 309,327,143 |
| Population - 2000 | 36,145 | 59,498 | 285,036,114 |
| Population - 1990 | 34,298 | 52,133 | 251,960,433 |
| Pop. 2000 to Now | 11.3% | 8.7% | 15.6% |
| Pop. 1990 to Now | 17.3% | 24.0% | 30.8% |
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| Population Density | 1,399.8 | 1,924.1 | 93.4 |
| Land Area | 28.9 | 34.0 | 3,531,905.4 |
| Water Area | 0.9 | 0.6 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Cedar Falls, IA | Janesville, WI | United States |
| Age 0 to 4 | 5.4% | 5.1% | 5.9% |
| Age 5 to 9 | 5.3% | 6.7% | 6.1% |
| Age 10 to 14 | 5.2% | 6.9% | 6.6% |
| Age 15 to 17 | 2.4% | 4.1% | 3.9% |
| Age 18 to 20 | 13.0% | 2.9% | 4.0% |
| Age 21 to 24 | 14.0% | 5.0% | 5.2% |
| Age 25 to 34 | 12.2% | 12.7% | 13.8% |
| Age 35 to 44 | 10.1% | 13.7% | 12.9% |
| Age 45 to 54 | 8.1% | 12.6% | 12.6% |
| Age 55 to 59 | 4.4% | 6.8% | 6.7% |
| Age 60 to 64 | 4.9% | 6.9% | 6.3% |
| Age 65 to 74 | 8.3% | 9.2% | 9.6% |
| Age 75 to 84 | 4.6% | 5.0% | 4.5% |
| Age 85 and over | 2.0% | 2.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Cedar Falls, IA | Janesville, WI | United States |
| White | 89.4% | 86.8% | 59.4% |
| Black | 1.3% | 3.0% | 12.2% |
| Asian | 4.4% | 1.7% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 1.9% | 2.5% | 3.2% |
| Hispanic | 2.7% | 5.7% | 18.4% |
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| Marriage & Family | | | |
| | Cedar Falls, IA | Janesville, WI | United States |
| Married Population | 43.7% | 48.7% | 49.8% |
| Currently Married | 43.0% | 47.5% | 48.0% |
| Married but Separated | 0.7% | 1.2% | 1.8% |
| Single Population | 56.3% | 51.3% | 50.2% |
| Never Married | 46.0% | 30.6% | 33.8% |
| Divorced | 6.2% | 14.4% | 10.8% |
| Widowed | 4.0% | 6.3% | 5.6% |
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| Household Size | 2.43 | 2.33 | 2.60 |
| Households | 15,254 | 27,743 | 124,010,992 |
| Family Households | 8,252 | 16,806 | 80,755,759 |
| Married couple, w/children | 32.8% | 26.5% | 30.5% |
| Married couple, no children | 52.4% | 45.2% | 42.9% |
| Non Family Households | 7,002 | 10,937 | 43,255,233 |
| Single householder, w/children | 8.5% | 18.2% | 15.8% |
| Single householder, no children | 6.3% | 10.2% | 10.8% |