| | Johnsonville, SC | Florence, SC | United States |
| Population | 1,170 | 39,816 | 329,725,481 |
| Female Population | 55.5% | 54.9% | 50.5% |
| Male Population | 44.5% | 45.1% | 49.5% |
| Median Age | 41.8 | 39.2 | 38.4 |
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| Population - 2010 | 1,490 | 37,928 | 309,327,143 |
| Population - 2000 | 1,418 | 30,248 | 285,036,114 |
| Population - 1990 | 1,415 | 29,813 | 251,960,433 |
| Pop. 2000 to Now | 3.8% | 27.2% | 15.6% |
| Pop. 1990 to Now | 4.0% | 29.0% | 30.8% |
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| Population Density | 553.5 | 1,789.4 | 93.4 |
| Land Area | 2.1 | 22.3 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Johnsonville, SC | Florence, SC | United States |
| Age 0 to 4 | 5.6% | 6.5% | 5.9% |
| Age 5 to 9 | 3.4% | 6.2% | 6.1% |
| Age 10 to 14 | 7.1% | 7.7% | 6.6% |
| Age 15 to 17 | 6.4% | 4.1% | 3.9% |
| Age 18 to 20 | 4.1% | 2.8% | 4.0% |
| Age 21 to 24 | 3.8% | 3.8% | 5.2% |
| Age 25 to 34 | 13.7% | 13.9% | 13.8% |
| Age 35 to 44 | 11.5% | 12.5% | 12.9% |
| Age 45 to 54 | 7.2% | 11.9% | 12.6% |
| Age 55 to 59 | 8.6% | 6.2% | 6.7% |
| Age 60 to 64 | 11.2% | 5.8% | 6.3% |
| Age 65 to 74 | 12.1% | 11.7% | 9.6% |
| Age 75 to 84 | 3.6% | 5.3% | 4.5% |
| Age 85 and over | 1.6% | 1.8% | 1.9% |
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| Race | | | |
| | Johnsonville, SC | Florence, SC | United States |
| White | 75.5% | 45.8% | 59.4% |
| Black | 19.5% | 47.4% | 12.2% |
| Asian | 1.8% | 2.6% | 5.6% |
| Native American | 0.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 2.5% | 1.2% | 3.2% |
| Hispanic | 0.8% | 2.0% | 18.4% |
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| Marriage & Family | | | |
| | Johnsonville, SC | Florence, SC | United States |
| Married Population | 53.7% | 47.9% | 49.8% |
| Currently Married | 50.9% | 44.7% | 48.0% |
| Married but Separated | 2.9% | 3.2% | 1.8% |
| Single Population | 46.3% | 52.1% | 50.2% |
| Never Married | 32.1% | 34.4% | 33.8% |
| Divorced | 8.8% | 10.9% | 10.8% |
| Widowed | 5.4% | 6.7% | 5.6% |
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| Household Size | 2.46 | 2.39 | 2.60 |
| Households | 472 | 16,412 | 124,010,992 |
| Family Households | 339 | 9,928 | 80,755,759 |
| Married couple, w/children | 22.1% | 27.9% | 30.5% |
| Married couple, no children | 51.9% | 38.8% | 42.9% |
| Non Family Households | 133 | 6,484 | 43,255,233 |
| Single householder, w/children | 15.0% | 22.0% | 15.8% |
| Single householder, no children | 10.9% | 11.2% | 10.8% |