| | St. Augustine South, FL | Naples, FL | United States |
| Population | 5,354 | 19,187 | 329,725,481 |
| Female Population | 50.5% | 53.4% | 50.5% |
| Male Population | 49.5% | 46.6% | 49.5% |
| Median Age | 50.1 | 66.3 | 38.4 |
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| Population - 2010 | 5,350 | 19,304 | 309,327,143 |
| Population - 2000 | 5,035 | 20,976 | 285,036,114 |
| Population - 1990 | 4,218 | 19,505 | 251,960,433 |
| Pop. 2000 to Now | 28.8% | 4.8% | 15.6% |
| Pop. 1990 to Now | 53.7% | 12.7% | 30.8% |
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| Population Density | 3,377.9 | 1,560.2 | 93.4 |
| Land Area | 1.6 | 12.3 | 3,531,905.4 |
| Water Area | 0.0 | 4.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | St. Augustine South, FL | Naples, FL | United States |
| Age 0 to 4 | 5.4% | 1.8% | 5.9% |
| Age 5 to 9 | 2.7% | 2.9% | 6.1% |
| Age 10 to 14 | 4.2% | 3.4% | 6.6% |
| Age 15 to 17 | 3.3% | 1.4% | 3.9% |
| Age 18 to 20 | 3.4% | 1.5% | 4.0% |
| Age 21 to 24 | 4.2% | 2.6% | 5.2% |
| Age 25 to 34 | 14.3% | 4.5% | 13.8% |
| Age 35 to 44 | 9.8% | 3.1% | 12.9% |
| Age 45 to 54 | 11.9% | 9.9% | 12.6% |
| Age 55 to 59 | 10.0% | 6.5% | 6.7% |
| Age 60 to 64 | 9.1% | 9.5% | 6.3% |
| Age 65 to 74 | 10.3% | 23.3% | 9.6% |
| Age 75 to 84 | 8.6% | 21.5% | 4.5% |
| Age 85 and over | 2.8% | 8.1% | 1.9% |
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| Race | | | |
| | St. Augustine South, FL | Naples, FL | United States |
| White | 87.2% | 87.7% | 59.4% |
| Black | 0.5% | 5.2% | 12.2% |
| Asian | 4.8% | 1.0% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 3.5% | 1.2% | 3.2% |
| Hispanic | 4.0% | 4.5% | 18.4% |
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| Marriage & Family | | | |
| | St. Augustine South, FL | Naples, FL | United States |
| Married Population | 48.3% | 62.3% | 49.8% |
| Currently Married | 47.5% | 61.6% | 48.0% |
| Married but Separated | 0.7% | 0.8% | 1.8% |
| Single Population | 51.7% | 37.7% | 50.2% |
| Never Married | 27.9% | 15.4% | 33.8% |
| Divorced | 18.3% | 11.5% | 10.8% |
| Widowed | 5.5% | 10.8% | 5.6% |
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| Household Size | 2.56 | 1.97 | 2.60 |
| Households | 2,082 | 9,594 | 124,010,992 |
| Family Households | 1,388 | 5,757 | 80,755,759 |
| Married couple, w/children | 26.4% | 10.5% | 30.5% |
| Married couple, no children | 49.9% | 79.9% | 42.9% |
| Non Family Households | 694 | 3,837 | 43,255,233 |
| Single householder, w/children | 10.7% | 4.0% | 15.8% |
| Single householder, no children | 13.0% | 5.6% | 10.8% |