| | Southold, NY | Southport, NC | United States |
| Population | 23,571 | 3,842 | 329,725,481 |
| Female Population | 52.7% | 60.6% | 50.5% |
| Male Population | 47.3% | 39.4% | 49.5% |
| Median Age | 56.1 | 63.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 21,985 | 2,934 | 309,327,143 |
| Population - 2000 | 20,599 | 2,351 | 285,036,114 |
| Population - 1990 | 19,836 | 2,369 | 251,960,433 |
| Pop. 2000 to Now | 8.2% | 73.9% | 15.6% |
| Pop. 1990 to Now | 12.3% | 72.6% | 30.8% |
| space4 | | | |
| Population Density | 438.4 | 971.9 | 93.4 |
| Land Area | 53.8 | 4.0 | 3,531,905.4 |
| Water Area | 349.9 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Southold, NY | Southport, NC | United States |
| Age 0 to 4 | 3.0% | 3.2% | 5.9% |
| Age 5 to 9 | 4.6% | 4.0% | 6.1% |
| Age 10 to 14 | 6.2% | 3.2% | 6.6% |
| Age 15 to 17 | 2.7% | 1.7% | 3.9% |
| Age 18 to 20 | 1.8% | 2.6% | 4.0% |
| Age 21 to 24 | 1.6% | 1.4% | 5.2% |
| Age 25 to 34 | 9.3% | 5.7% | 13.8% |
| Age 35 to 44 | 8.9% | 7.3% | 12.9% |
| Age 45 to 54 | 10.8% | 10.2% | 12.6% |
| Age 55 to 59 | 8.4% | 6.2% | 6.7% |
| Age 60 to 64 | 11.1% | 11.4% | 6.3% |
| Age 65 to 74 | 17.3% | 30.3% | 9.6% |
| Age 75 to 84 | 9.0% | 7.9% | 4.5% |
| Age 85 and over | 5.1% | 5.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Southold, NY | Southport, NC | United States |
| White | 86.9% | 84.5% | 59.4% |
| Black | 1.2% | 12.2% | 12.2% |
| Asian | 1.2% | 0.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.3% | 0.0% | 0.4% |
| Two or More Races | 1.3% | 1.0% | 3.2% |
| Hispanic | 9.1% | 2.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Southold, NY | Southport, NC | United States |
| Married Population | 60.5% | 64.9% | 49.8% |
| Currently Married | 59.4% | 63.2% | 48.0% |
| Married but Separated | 1.1% | 1.7% | 1.8% |
| Single Population | 39.5% | 35.1% | 50.2% |
| Never Married | 21.3% | 15.6% | 33.8% |
| Divorced | 9.5% | 11.7% | 10.8% |
| Widowed | 8.7% | 7.7% | 5.6% |
| space5 | | | |
| Household Size | 2.26 | 2.12 | 2.60 |
| Households | 10,252 | 1,739 | 124,010,992 |
| Family Households | 6,764 | 1,248 | 80,755,759 |
| Married couple, w/children | 21.3% | 12.7% | 30.5% |
| Married couple, no children | 63.2% | 69.8% | 42.9% |
| Non Family Households | 3,488 | 491 | 43,255,233 |
| Single householder, w/children | 7.1% | 9.9% | 15.8% |
| Single householder, no children | 8.5% | 7.5% | 10.8% |