| | St. Robert, MO | Wahiawa, HI | United States |
| Population | 5,191 | 17,357 | 329,725,481 |
| Female Population | 39.2% | 50.0% | 50.5% |
| Male Population | 60.8% | 50.0% | 49.5% |
| Median Age | 31.4 | 42.3 | 38.4 |
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| Population - 2010 | 4,709 | 17,208 | 309,327,143 |
| Population - 2000 | 2,760 | 16,151 | 285,036,114 |
| Population - 1990 | 1,730 | 17,386 | 251,960,433 |
| Pop. 2000 to Now | 130.4% | 5.6% | 15.6% |
| Pop. 1990 to Now | 267.5% | -1.9% | 30.8% |
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| Population Density | 657.9 | 8,356.8 | 93.4 |
| Land Area | 7.9 | 2.1 | 3,531,905.4 |
| Water Area | 0.0 | 0.3 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | St. Robert, MO | Wahiawa, HI | United States |
| Age 0 to 4 | 9.8% | 4.0% | 5.9% |
| Age 5 to 9 | 5.2% | 5.4% | 6.1% |
| Age 10 to 14 | 7.6% | 7.2% | 6.6% |
| Age 15 to 17 | 2.7% | 5.2% | 3.9% |
| Age 18 to 20 | 6.3% | 2.6% | 4.0% |
| Age 21 to 24 | 4.7% | 4.8% | 5.2% |
| Age 25 to 34 | 19.7% | 11.3% | 13.8% |
| Age 35 to 44 | 21.1% | 12.1% | 12.9% |
| Age 45 to 54 | 9.5% | 11.8% | 12.6% |
| Age 55 to 59 | 1.9% | 8.3% | 6.7% |
| Age 60 to 64 | 1.1% | 7.0% | 6.3% |
| Age 65 to 74 | 5.0% | 9.2% | 9.6% |
| Age 75 to 84 | 5.0% | 6.2% | 4.5% |
| Age 85 and over | 0.4% | 4.8% | 1.9% |
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| Race | | | |
| | St. Robert, MO | Wahiawa, HI | United States |
| White | 57.5% | 10.4% | 59.4% |
| Black | 15.0% | 2.2% | 12.2% |
| Asian | 6.9% | 42.5% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 11.0% | 0.2% |
| Other | 2.8% | 0.1% | 0.4% |
| Two or More Races | 7.6% | 20.1% | 3.2% |
| Hispanic | 10.3% | 13.7% | 18.4% |
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| Marriage & Family | | | |
| | St. Robert, MO | Wahiawa, HI | United States |
| Married Population | 62.3% | 48.8% | 49.8% |
| Currently Married | 59.3% | 46.6% | 48.0% |
| Married but Separated | 3.0% | 2.2% | 1.8% |
| Single Population | 37.7% | 51.2% | 50.2% |
| Never Married | 26.1% | 35.0% | 33.8% |
| Divorced | 7.3% | 9.5% | 10.8% |
| Widowed | 4.3% | 6.7% | 5.6% |
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| Household Size | 2.38 | 2.85 | 2.60 |
| Households | 2,176 | 6,037 | 124,010,992 |
| Family Households | 1,475 | 4,289 | 80,755,759 |
| Married couple, w/children | 43.8% | 22.2% | 30.5% |
| Married couple, no children | 34.0% | 41.9% | 42.9% |
| Non Family Households | 701 | 1,748 | 43,255,233 |
| Single householder, w/children | 20.5% | 19.8% | 15.8% |
| Single householder, no children | 1.7% | 16.1% | 10.8% |