| | Oak Island, NC | Marion, SC | United States |
| Population | 8,252 | 6,472 | 329,725,481 |
| Female Population | 50.9% | 53.0% | 50.5% |
| Male Population | 49.2% | 47.0% | 49.5% |
| Median Age | 60.3 | 42.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 6,816 | 6,880 | 309,327,143 |
| Population - 2000 | 6,571 | 7,042 | 285,036,114 |
| Population - 1990 | 4,753 | 7,658 | 251,960,433 |
| Pop. 2000 to Now | 32.9% | -12.0% | 15.6% |
| Pop. 1990 to Now | 83.8% | -19.0% | 30.8% |
| space4 | | | |
| Population Density | 442.5 | 1,463.9 | 93.4 |
| Land Area | 18.7 | 4.4 | 3,531,905.4 |
| Water Area | 1.4 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Oak Island, NC | Marion, SC | United States |
| Age 0 to 4 | 1.7% | 7.1% | 5.9% |
| Age 5 to 9 | 1.6% | 6.6% | 6.1% |
| Age 10 to 14 | 3.0% | 6.0% | 6.6% |
| Age 15 to 17 | 2.2% | 2.1% | 3.9% |
| Age 18 to 20 | 0.9% | 1.7% | 4.0% |
| Age 21 to 24 | 1.5% | 1.1% | 5.2% |
| Age 25 to 34 | 5.6% | 17.1% | 13.8% |
| Age 35 to 44 | 5.3% | 11.5% | 12.9% |
| Age 45 to 54 | 14.3% | 13.8% | 12.6% |
| Age 55 to 59 | 12.9% | 5.9% | 6.7% |
| Age 60 to 64 | 13.8% | 6.4% | 6.3% |
| Age 65 to 74 | 26.2% | 14.0% | 9.6% |
| Age 75 to 84 | 9.2% | 5.1% | 4.5% |
| Age 85 and over | 1.7% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Oak Island, NC | Marion, SC | United States |
| White | 94.8% | 20.4% | 59.4% |
| Black | 0.4% | 77.4% | 12.2% |
| Asian | 0.9% | 1.3% | 5.6% |
| Native American | 0.5% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.2% | 0.9% | 3.2% |
| Hispanic | 1.1% | 0.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Oak Island, NC | Marion, SC | United States |
| Married Population | 62.7% | 27.7% | 49.8% |
| Currently Married | 61.9% | 22.2% | 48.0% |
| Married but Separated | 0.8% | 5.5% | 1.8% |
| Single Population | 37.3% | 72.3% | 50.2% |
| Never Married | 15.7% | 54.2% | 33.8% |
| Divorced | 15.9% | 8.6% | 10.8% |
| Widowed | 5.6% | 9.5% | 5.6% |
| space5 | | | |
| Household Size | 2.18 | 2.68 | 2.60 |
| Households | 3,778 | 2,401 | 124,010,992 |
| Family Households | 2,482 | 1,562 | 80,755,759 |
| Married couple, w/children | 10.0% | 4.8% | 30.5% |
| Married couple, no children | 79.1% | 27.6% | 42.9% |
| Non Family Households | 1,296 | 839 | 43,255,233 |
| Single householder, w/children | 6.1% | 34.3% | 15.8% |
| Single householder, no children | 4.8% | 33.3% | 10.8% |