| | Brooklyn, IA | Clinton, IA | United States |
| Population | 1,662 | 24,651 | 329,725,481 |
| Female Population | 53.2% | 50.9% | 50.5% |
| Male Population | 46.8% | 49.1% | 49.5% |
| Median Age | 32.4 | 42.1 | 38.4 |
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| Population - 2010 | 1,475 | 26,849 | 309,327,143 |
| Population - 2000 | 1,367 | 27,772 | 285,036,114 |
| Population - 1990 | 1,439 | 29,201 | 251,960,433 |
| Pop. 2000 to Now | 1.7% | -9.8% | 15.6% |
| Pop. 1990 to Now | -3.4% | -14.3% | 30.8% |
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| Population Density | 1,323.3 | 701.2 | 93.4 |
| Land Area | 1.3 | 35.2 | 3,531,905.4 |
| Water Area | 0.0 | 2.9 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Brooklyn, IA | Clinton, IA | United States |
| Age 0 to 4 | 11.5% | 5.7% | 5.9% |
| Age 5 to 9 | 7.5% | 4.9% | 6.1% |
| Age 10 to 14 | 6.3% | 6.5% | 6.6% |
| Age 15 to 17 | 2.9% | 3.8% | 3.9% |
| Age 18 to 20 | 1.7% | 3.7% | 4.0% |
| Age 21 to 24 | 9.1% | 3.9% | 5.2% |
| Age 25 to 34 | 14.0% | 13.3% | 13.8% |
| Age 35 to 44 | 15.8% | 11.3% | 12.9% |
| Age 45 to 54 | 7.3% | 12.0% | 12.6% |
| Age 55 to 59 | 4.5% | 7.7% | 6.7% |
| Age 60 to 64 | 5.0% | 7.6% | 6.3% |
| Age 65 to 74 | 8.4% | 10.5% | 9.6% |
| Age 75 to 84 | 3.8% | 6.1% | 4.5% |
| Age 85 and over | 2.1% | 3.0% | 1.9% |
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| Race | | | |
| | Brooklyn, IA | Clinton, IA | United States |
| White | 97.2% | 86.3% | 59.4% |
| Black | 0.1% | 5.1% | 12.2% |
| Asian | 0.0% | 0.6% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 0.0% | 3.2% | 3.2% |
| Hispanic | 2.7% | 4.6% | 18.4% |
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| Marriage & Family | | | |
| | Brooklyn, IA | Clinton, IA | United States |
| Married Population | 47.3% | 45.5% | 49.8% |
| Currently Married | 45.9% | 43.1% | 48.0% |
| Married but Separated | 1.4% | 2.4% | 1.8% |
| Single Population | 52.7% | 54.5% | 50.2% |
| Never Married | 34.1% | 31.9% | 33.8% |
| Divorced | 11.9% | 14.3% | 10.8% |
| Widowed | 6.6% | 8.3% | 5.6% |
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| Household Size | 2.52 | 2.33 | 2.60 |
| Households | 646 | 10,356 | 124,010,992 |
| Family Households | 363 | 5,936 | 80,755,759 |
| Married couple, w/children | 36.9% | 24.3% | 30.5% |
| Married couple, no children | 42.4% | 46.8% | 42.9% |
| Non Family Households | 283 | 4,420 | 43,255,233 |
| Single householder, w/children | 13.8% | 17.8% | 15.8% |
| Single householder, no children | 6.9% | 11.0% | 10.8% |