| | Atlantic Beach, FL | Mount Pleasant, SC | United States |
| Population | 13,404 | 88,900 | 329,725,481 |
| Female Population | 52.9% | 51.0% | 50.5% |
| Male Population | 47.1% | 49.0% | 49.5% |
| Median Age | 49.7 | 41.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 12,663 | 68,553 | 309,327,143 |
| Population - 2000 | 13,368 | 47,609 | 285,036,114 |
| Population - 1990 | 11,636 | 30,108 | 251,960,433 |
| Pop. 2000 to Now | 3.6% | 94.9% | 15.6% |
| Pop. 1990 to Now | 19.0% | 208.2% | 30.8% |
| space4 | | | |
| Population Density | 3,844.0 | 1,969.1 | 93.4 |
| Land Area | 3.5 | 45.1 | 3,531,905.4 |
| Water Area | 9.5 | 7.5 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Atlantic Beach, FL | Mount Pleasant, SC | United States |
| Age 0 to 4 | 3.6% | 5.7% | 5.9% |
| Age 5 to 9 | 4.4% | 5.3% | 6.1% |
| Age 10 to 14 | 5.7% | 7.6% | 6.6% |
| Age 15 to 17 | 3.6% | 4.2% | 3.9% |
| Age 18 to 20 | 1.8% | 1.6% | 4.0% |
| Age 21 to 24 | 4.5% | 2.8% | 5.2% |
| Age 25 to 34 | 10.4% | 12.7% | 13.8% |
| Age 35 to 44 | 10.5% | 15.5% | 12.9% |
| Age 45 to 54 | 14.3% | 13.7% | 12.6% |
| Age 55 to 59 | 9.9% | 6.7% | 6.7% |
| Age 60 to 64 | 9.0% | 6.8% | 6.3% |
| Age 65 to 74 | 12.5% | 11.1% | 9.6% |
| Age 75 to 84 | 6.0% | 4.2% | 4.5% |
| Age 85 and over | 3.8% | 2.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Atlantic Beach, FL | Mount Pleasant, SC | United States |
| White | 80.2% | 89.9% | 59.4% |
| Black | 6.0% | 3.3% | 12.2% |
| Asian | 3.1% | 2.0% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 1.1% | 0.1% | 0.4% |
| Two or More Races | 3.6% | 2.3% | 3.2% |
| Hispanic | 6.0% | 2.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Atlantic Beach, FL | Mount Pleasant, SC | United States |
| Married Population | 53.6% | 61.6% | 49.8% |
| Currently Married | 52.5% | 61.0% | 48.0% |
| Married but Separated | 1.1% | 0.6% | 1.8% |
| Single Population | 46.4% | 38.4% | 50.2% |
| Never Married | 27.3% | 24.4% | 33.8% |
| Divorced | 12.5% | 8.7% | 10.8% |
| Widowed | 6.7% | 5.2% | 5.6% |
| space5 | | | |
| Household Size | 2.24 | 2.41 | 2.60 |
| Households | 5,960 | 36,673 | 124,010,992 |
| Family Households | 3,623 | 24,488 | 80,755,759 |
| Married couple, w/children | 21.9% | 38.0% | 30.5% |
| Married couple, no children | 55.0% | 48.7% | 42.9% |
| Non Family Households | 2,337 | 12,185 | 43,255,233 |
| Single householder, w/children | 9.9% | 8.4% | 15.8% |
| Single householder, no children | 13.2% | 4.9% | 10.8% |