| | San Diego Country Estates, CA | West Dennis, MA | United States |
| Population | 10,366 | 2,703 | 329,725,481 |
| Female Population | 47.5% | 53.0% | 50.5% |
| Male Population | 52.5% | 47.0% | 49.5% |
| Median Age | 43.8 | 57.9 | 38.4 |
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| Population - 2010 | 10,657 | 2,022 | 309,327,143 |
| Population - 2000 | 9,262 | 2,570 | 285,036,114 |
| Population - 1990 | 6,874 | 2,307 | 251,960,433 |
| Pop. 2000 to Now | 16.6% | -10.5% | 15.6% |
| Pop. 1990 to Now | 57.1% | -0.4% | 30.8% |
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| Population Density | 617.6 | 828.9 | 93.4 |
| Land Area | 16.8 | 3.3 | 3,531,905.4 |
| Water Area | 0.0 | 0.9 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | San Diego Country Estates, CA | West Dennis, MA | United States |
| Age 0 to 4 | 5.3% | 1.7% | 5.9% |
| Age 5 to 9 | 6.2% | 0.6% | 6.1% |
| Age 10 to 14 | 7.3% | 1.1% | 6.6% |
| Age 15 to 17 | 5.7% | 3.6% | 3.9% |
| Age 18 to 20 | 4.1% | 1.9% | 4.0% |
| Age 21 to 24 | 3.3% | 10.7% | 5.2% |
| Age 25 to 34 | 9.2% | 4.6% | 13.8% |
| Age 35 to 44 | 10.2% | 6.8% | 12.9% |
| Age 45 to 54 | 19.1% | 13.1% | 12.6% |
| Age 55 to 59 | 9.1% | 11.5% | 6.7% |
| Age 60 to 64 | 6.1% | 8.3% | 6.3% |
| Age 65 to 74 | 8.8% | 21.1% | 9.6% |
| Age 75 to 84 | 4.9% | 9.8% | 4.5% |
| Age 85 and over | 0.7% | 5.2% | 1.9% |
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| Race | | | |
| | San Diego Country Estates, CA | West Dennis, MA | United States |
| White | 72.9% | 77.9% | 59.4% |
| Black | 0.8% | 2.5% | 12.2% |
| Asian | 1.7% | 0.0% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.3% | 0.2% |
| Other | 0.2% | 0.4% | 0.4% |
| Two or More Races | 3.8% | 0.7% | 3.2% |
| Hispanic | 20.4% | 18.1% | 18.4% |
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| Marriage & Family | | | |
| | San Diego Country Estates, CA | West Dennis, MA | United States |
| Married Population | 62.6% | 46.3% | 49.8% |
| Currently Married | 60.9% | 45.8% | 48.0% |
| Married but Separated | 1.8% | 0.5% | 1.8% |
| Single Population | 37.4% | 53.7% | 50.2% |
| Never Married | 24.5% | 35.7% | 33.8% |
| Divorced | 8.3% | 10.2% | 10.8% |
| Widowed | 4.6% | 7.8% | 5.6% |
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| Household Size | 3.01 | 1.98 | 2.60 |
| Households | 3,440 | 1,362 | 124,010,992 |
| Family Households | 2,920 | 724 | 80,755,759 |
| Married couple, w/children | 37.3% | 4.4% | 30.5% |
| Married couple, no children | 48.1% | 63.5% | 42.9% |
| Non Family Households | 520 | 638 | 43,255,233 |
| Single householder, w/children | 6.8% | 17.7% | 15.8% |
| Single householder, no children | 7.8% | 14.4% | 10.8% |