| | Port Jefferson Station, NY | Irmo, SC | United States |
| Population | 7,716 | 11,581 | 329,725,481 |
| Female Population | 51.9% | 54.2% | 50.5% |
| Male Population | 48.1% | 45.8% | 49.5% |
| Median Age | 38.6 | 39.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 7,521 | 11,167 | 309,327,143 |
| Population - 2000 | 7,527 | 11,039 | 285,036,114 |
| Population - 1990 | 7,232 | 11,280 | 251,960,433 |
| Pop. 2000 to Now | -4.1% | 15.4% | 15.6% |
| Pop. 1990 to Now | -0.2% | 12.9% | 30.8% |
| space4 | | | |
| Population Density | 2,909.5 | 1,714.4 | 93.4 |
| Land Area | 2.7 | 6.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Port Jefferson Station, NY | Irmo, SC | United States |
| Age 0 to 4 | 7.0% | 4.1% | 5.9% |
| Age 5 to 9 | 7.2% | 6.7% | 6.1% |
| Age 10 to 14 | 2.9% | 4.9% | 6.6% |
| Age 15 to 17 | 3.4% | 4.6% | 3.9% |
| Age 18 to 20 | 3.2% | 2.2% | 4.0% |
| Age 21 to 24 | 8.0% | 4.0% | 5.2% |
| Age 25 to 34 | 13.7% | 17.6% | 13.8% |
| Age 35 to 44 | 12.4% | 11.1% | 12.9% |
| Age 45 to 54 | 11.0% | 12.7% | 12.6% |
| Age 55 to 59 | 8.6% | 11.8% | 6.7% |
| Age 60 to 64 | 7.0% | 5.0% | 6.3% |
| Age 65 to 74 | 9.1% | 8.8% | 9.6% |
| Age 75 to 84 | 4.5% | 5.0% | 4.5% |
| Age 85 and over | 2.0% | 1.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Port Jefferson Station, NY | Irmo, SC | United States |
| White | 73.3% | 65.4% | 59.4% |
| Black | 2.0% | 25.6% | 12.2% |
| Asian | 1.7% | 3.9% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.0% | 2.7% | 3.2% |
| Hispanic | 21.1% | 2.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Port Jefferson Station, NY | Irmo, SC | United States |
| Married Population | 59.7% | 57.7% | 49.8% |
| Currently Married | 58.4% | 56.8% | 48.0% |
| Married but Separated | 1.3% | 0.9% | 1.8% |
| Single Population | 40.3% | 42.3% | 50.2% |
| Never Married | 32.6% | 28.4% | 33.8% |
| Divorced | 4.4% | 9.6% | 10.8% |
| Widowed | 3.2% | 4.4% | 5.6% |
| space5 | | | |
| Household Size | 2.97 | 2.53 | 2.60 |
| Households | 2,579 | 4,567 | 124,010,992 |
| Family Households | 1,974 | 3,350 | 80,755,759 |
| Married couple, w/children | 35.7% | 26.1% | 30.5% |
| Married couple, no children | 52.3% | 54.2% | 42.9% |
| Non Family Households | 605 | 1,217 | 43,255,233 |
| Single householder, w/children | 8.1% | 15.7% | 15.8% |
| Single householder, no children | 4.0% | 4.0% | 10.8% |