| | Dewey Beach, DE | St. Michaels, MD | United States |
| Population | 347 | 1,483 | 329,725,481 |
| Female Population | 51.0% | 60.2% | 50.5% |
| Male Population | 49.0% | 39.9% | 49.5% |
| Median Age | 60 | 51.3 | 38.4 |
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| Population - 2010 | 340 | 1,027 | 309,327,143 |
| Population - 2000 | 301 | 1,193 | 285,036,114 |
| Population - 1990 | 204 | 1,301 | 251,960,433 |
| Pop. 2000 to Now | 36.5% | -13.8% | 15.6% |
| Pop. 1990 to Now | 101.5% | -20.9% | 30.8% |
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| Population Density | 1,048.3 | 1,278.5 | 93.4 |
| Land Area | 0.3 | 1.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Dewey Beach, DE | St. Michaels, MD | United States |
| Age 0 to 4 | 0.0% | 1.3% | 5.9% |
| Age 5 to 9 | 0.0% | 4.5% | 6.1% |
| Age 10 to 14 | 1.7% | 4.2% | 6.6% |
| Age 15 to 17 | 5.5% | 1.9% | 3.9% |
| Age 18 to 20 | 1.4% | 0.3% | 4.0% |
| Age 21 to 24 | 1.4% | 10.7% | 5.2% |
| Age 25 to 34 | 8.6% | 9.7% | 13.8% |
| Age 35 to 44 | 4.9% | 6.8% | 12.9% |
| Age 45 to 54 | 12.1% | 12.5% | 12.6% |
| Age 55 to 59 | 14.4% | 5.9% | 6.7% |
| Age 60 to 64 | 11.2% | 9.5% | 6.3% |
| Age 65 to 74 | 19.0% | 21.5% | 9.6% |
| Age 75 to 84 | 18.7% | 7.8% | 4.5% |
| Age 85 and over | 0.9% | 3.4% | 1.9% |
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| Race | | | |
| | Dewey Beach, DE | St. Michaels, MD | United States |
| White | 93.9% | 67.9% | 59.4% |
| Black | 0.0% | 24.3% | 12.2% |
| Asian | 0.0% | 0.4% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 3.7% | 1.3% | 3.2% |
| Hispanic | 2.3% | 6.1% | 18.4% |
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| Marriage & Family | | | |
| | Dewey Beach, DE | St. Michaels, MD | United States |
| Married Population | 71.3% | 55.3% | 49.8% |
| Currently Married | 70.1% | 53.7% | 48.0% |
| Married but Separated | 1.2% | 1.6% | 1.8% |
| Single Population | 28.7% | 44.7% | 50.2% |
| Never Married | 18.5% | 28.1% | 33.8% |
| Divorced | 5.9% | 13.0% | 10.8% |
| Widowed | 4.4% | 3.6% | 5.6% |
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| Household Size | 2.02 | 2.07 | 2.60 |
| Households | 172 | 716 | 124,010,992 |
| Family Households | 119 | 505 | 80,755,759 |
| Married couple, w/children | 6.7% | 8.1% | 30.5% |
| Married couple, no children | 82.4% | 60.6% | 42.9% |
| Non Family Households | 53 | 211 | 43,255,233 |
| Single householder, w/children | 6.7% | 18.8% | 15.8% |
| Single householder, no children | 4.2% | 12.5% | 10.8% |