| | Allyn, WA | Signal Mountain, TN | United States |
| Population | 2,363 | 8,770 | 329,725,481 |
| Female Population | 47.1% | 51.8% | 50.5% |
| Male Population | 52.9% | 48.2% | 49.5% |
| Median Age | 53.6 | 43.9 | 38.4 |
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| Population - 2010 | 1,381 | 8,269 | 309,327,143 |
| Population - 2000 | 1,111 | 7,429 | 285,036,114 |
| Population - 1990 | 882 | 7,034 | 251,960,433 |
| Pop. 2000 to Now | 166.8% | 16.3% | 15.6% |
| Pop. 1990 to Now | 236.1% | 22.8% | 30.8% |
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| Population Density | 1,480.6 | 1,049.6 | 93.4 |
| Land Area | 1.6 | 8.4 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Allyn, WA | Signal Mountain, TN | United States |
| Age 0 to 4 | 0.0% | 3.4% | 5.9% |
| Age 5 to 9 | 9.0% | 10.3% | 6.1% |
| Age 10 to 14 | 5.5% | 11.0% | 6.6% |
| Age 15 to 17 | 3.5% | 4.1% | 3.9% |
| Age 18 to 20 | 0.0% | 2.1% | 4.0% |
| Age 21 to 24 | 3.3% | 0.8% | 5.2% |
| Age 25 to 34 | 9.8% | 4.9% | 13.8% |
| Age 35 to 44 | 13.0% | 14.4% | 12.9% |
| Age 45 to 54 | 8.7% | 14.9% | 12.6% |
| Age 55 to 59 | 11.7% | 4.5% | 6.7% |
| Age 60 to 64 | 10.4% | 5.7% | 6.3% |
| Age 65 to 74 | 20.1% | 11.7% | 9.6% |
| Age 75 to 84 | 3.2% | 6.7% | 4.5% |
| Age 85 and over | 1.8% | 5.4% | 1.9% |
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| Race | | | |
| | Allyn, WA | Signal Mountain, TN | United States |
| White | 94.8% | 96.0% | 59.4% |
| Black | 0.0% | 0.3% | 12.2% |
| Asian | 1.0% | 0.3% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 2.2% | 2.6% | 3.2% |
| Hispanic | 1.9% | 0.5% | 18.4% |
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| Marriage & Family | | | |
| | Allyn, WA | Signal Mountain, TN | United States |
| Married Population | 63.5% | 70.0% | 49.8% |
| Currently Married | 63.5% | 69.4% | 48.0% |
| Married but Separated | 0.0% | 0.7% | 1.8% |
| Single Population | 36.5% | 30.0% | 50.2% |
| Never Married | 20.0% | 14.8% | 33.8% |
| Divorced | 13.7% | 8.4% | 10.8% |
| Widowed | 2.8% | 6.8% | 5.6% |
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| Household Size | 2.32 | 2.58 | 2.60 |
| Households | 1,014 | 3,341 | 124,010,992 |
| Family Households | 701 | 2,456 | 80,755,759 |
| Married couple, w/children | 21.5% | 43.9% | 30.5% |
| Married couple, no children | 72.5% | 47.1% | 42.9% |
| Non Family Households | 313 | 885 | 43,255,233 |
| Single householder, w/children | 0.0% | 6.3% | 15.8% |
| Single householder, no children | 6.0% | 2.8% | 10.8% |