| | St. Augustine Beach, FL | Livingston, MT | United States |
| Population | 6,688 | 8,110 | 329,725,481 |
| Female Population | 49.5% | 50.6% | 50.5% |
| Male Population | 50.5% | 49.4% | 49.5% |
| Median Age | 49.2 | 41.6 | 38.4 |
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| Population - 2010 | 6,184 | 7,031 | 309,327,143 |
| Population - 2000 | 4,683 | 6,851 | 285,036,114 |
| Population - 1990 | 3,657 | 6,701 | 251,960,433 |
| Pop. 2000 to Now | 52.4% | 15.3% | 15.6% |
| Pop. 1990 to Now | 95.2% | 17.9% | 30.8% |
| space4 | | | |
| Population Density | 3,162.2 | 1,437.7 | 93.4 |
| Land Area | 2.1 | 5.6 | 3,531,905.4 |
| Water Area | 0.1 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | St. Augustine Beach, FL | Livingston, MT | United States |
| Age 0 to 4 | 2.8% | 6.1% | 5.9% |
| Age 5 to 9 | 3.3% | 3.8% | 6.1% |
| Age 10 to 14 | 7.0% | 6.7% | 6.6% |
| Age 15 to 17 | 3.8% | 3.3% | 3.9% |
| Age 18 to 20 | 3.6% | 2.3% | 4.0% |
| Age 21 to 24 | 5.5% | 3.9% | 5.2% |
| Age 25 to 34 | 2.5% | 15.4% | 13.8% |
| Age 35 to 44 | 16.7% | 15.6% | 12.9% |
| Age 45 to 54 | 11.7% | 10.2% | 12.6% |
| Age 55 to 59 | 7.5% | 7.1% | 6.7% |
| Age 60 to 64 | 12.7% | 5.6% | 6.3% |
| Age 65 to 74 | 14.2% | 12.1% | 9.6% |
| Age 75 to 84 | 6.8% | 4.7% | 4.5% |
| Age 85 and over | 1.9% | 3.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | St. Augustine Beach, FL | Livingston, MT | United States |
| White | 94.3% | 93.9% | 59.4% |
| Black | 0.1% | 0.5% | 12.2% |
| Asian | 0.4% | 0.3% | 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 | 1.2% | 1.9% | 3.2% |
| Hispanic | 4.0% | 3.1% | 18.4% |
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| Marriage & Family | | | |
| | St. Augustine Beach, FL | Livingston, MT | United States |
| Married Population | 52.4% | 41.6% | 49.8% |
| Currently Married | 51.7% | 41.3% | 48.0% |
| Married but Separated | 0.7% | 0.3% | 1.8% |
| Single Population | 47.6% | 58.4% | 50.2% |
| Never Married | 25.3% | 32.0% | 33.8% |
| Divorced | 14.2% | 19.5% | 10.8% |
| Widowed | 8.1% | 6.9% | 5.6% |
| space5 | | | |
| Household Size | 2.39 | 2.09 | 2.60 |
| Households | 2,799 | 3,824 | 124,010,992 |
| Family Households | 1,681 | 1,836 | 80,755,759 |
| Married couple, w/children | 28.7% | 26.5% | 30.5% |
| Married couple, no children | 55.3% | 47.2% | 42.9% |
| Non Family Households | 1,118 | 1,988 | 43,255,233 |
| Single householder, w/children | 6.9% | 19.3% | 15.8% |
| Single householder, no children | 9.0% | 7.0% | 10.8% |