| | Seabeck, WA | Vashon, WA | United States |
| Population | 860 | 10,886 | 329,725,481 |
| Female Population | 46.5% | 53.6% | 50.5% |
| Male Population | 53.5% | 46.4% | 49.5% |
| Median Age | 46.9 | 49.7 | 38.4 |
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| Population - 2010 | 801 | 9,927 | 309,327,143 |
| Population - 2000 | 963 | 10,123 | 285,036,114 |
| Population - 1990 | 726 | 9,309 | 251,960,433 |
| Pop. 2000 to Now | 24.6% | 1.8% | 15.6% |
| Pop. 1990 to Now | 65.3% | 10.7% | 30.8% |
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| Population Density | 259.0 | 294.8 | 93.4 |
| Land Area | 3.3 | 36.9 | 3,531,905.4 |
| Water Area | 0.9 | 43.9 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Seabeck, WA | Vashon, WA | United States |
| Age 0 to 4 | 4.7% | 2.8% | 5.9% |
| Age 5 to 9 | 1.9% | 2.7% | 6.1% |
| Age 10 to 14 | 8.6% | 8.4% | 6.6% |
| Age 15 to 17 | 4.8% | 4.5% | 3.9% |
| Age 18 to 20 | 5.0% | 1.8% | 4.0% |
| Age 21 to 24 | 0.7% | 3.1% | 5.2% |
| Age 25 to 34 | 10.7% | 7.8% | 13.8% |
| Age 35 to 44 | 11.5% | 11.8% | 12.9% |
| Age 45 to 54 | 20.1% | 14.5% | 12.6% |
| Age 55 to 59 | 5.3% | 7.1% | 6.7% |
| Age 60 to 64 | 6.6% | 9.8% | 6.3% |
| Age 65 to 74 | 12.4% | 17.2% | 9.6% |
| Age 75 to 84 | 7.7% | 5.3% | 4.5% |
| Age 85 and over | 0.0% | 3.2% | 1.9% |
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| Race | | | |
| | Seabeck, WA | Vashon, WA | United States |
| White | 72.8% | 89.3% | 59.4% |
| Black | 0.0% | 0.0% | 12.2% |
| Asian | 2.2% | 1.0% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 1.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 8.6% | 3.7% | 3.2% |
| Hispanic | 16.4% | 4.8% | 18.4% |
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| Marriage & Family | | | |
| | Seabeck, WA | Vashon, WA | United States |
| Married Population | 63.6% | 57.3% | 49.8% |
| Currently Married | 62.3% | 55.5% | 48.0% |
| Married but Separated | 1.2% | 1.7% | 1.8% |
| Single Population | 36.4% | 42.7% | 50.2% |
| Never Married | 29.7% | 23.6% | 33.8% |
| Divorced | 0.8% | 12.2% | 10.8% |
| Widowed | 5.9% | 6.9% | 5.6% |
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| Household Size | 2.27 | 2.37 | 2.60 |
| Households | 379 | 4,579 | 124,010,992 |
| Family Households | 276 | 2,888 | 80,755,759 |
| Married couple, w/children | 31.9% | 29.2% | 30.5% |
| Married couple, no children | 47.1% | 52.3% | 42.9% |
| Non Family Households | 103 | 1,691 | 43,255,233 |
| Single householder, w/children | 18.8% | 8.5% | 15.8% |
| Single householder, no children | 2.2% | 10.1% | 10.8% |