| | South Portland, ME | Southwest Harbor, ME | United States |
| Population | 26,428 | 1,535 | 329,725,481 |
| Female Population | 51.0% | 59.4% | 50.5% |
| Male Population | 49.1% | 40.7% | 49.5% |
| Median Age | 43.2 | 55.5 | 38.4 |
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| Population - 2010 | 24,994 | 1,768 | 309,327,143 |
| Population - 2000 | 23,324 | 1,966 | 285,036,114 |
| Population - 1990 | 23,163 | 1,952 | 251,960,433 |
| Pop. 2000 to Now | 11.3% | -8.8% | 15.6% |
| Pop. 1990 to Now | 12.0% | -8.2% | 30.8% |
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| Population Density | 2,192.7 | 113.6 | 93.4 |
| Land Area | 12.1 | 13.5 | 3,531,905.4 |
| Water Area | 2.0 | 9.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | South Portland, ME | Southwest Harbor, ME | United States |
| Age 0 to 4 | 3.4% | 7.3% | 5.9% |
| Age 5 to 9 | 3.1% | 7.9% | 6.1% |
| Age 10 to 14 | 4.9% | 0.0% | 6.6% |
| Age 15 to 17 | 3.8% | 1.2% | 3.9% |
| Age 18 to 20 | 3.7% | 6.5% | 4.0% |
| Age 21 to 24 | 7.0% | 1.7% | 5.2% |
| Age 25 to 34 | 15.0% | 11.3% | 13.8% |
| Age 35 to 44 | 11.2% | 5.7% | 12.9% |
| Age 45 to 54 | 12.3% | 6.5% | 12.6% |
| Age 55 to 59 | 8.6% | 11.0% | 6.7% |
| Age 60 to 64 | 6.5% | 7.7% | 6.3% |
| Age 65 to 74 | 12.5% | 17.0% | 9.6% |
| Age 75 to 84 | 6.1% | 9.5% | 4.5% |
| Age 85 and over | 1.8% | 6.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | South Portland, ME | Southwest Harbor, ME | United States |
| White | 87.0% | 98.7% | 59.4% |
| Black | 5.0% | 0.7% | 12.2% |
| Asian | 2.1% | 0.0% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.8% | 0.0% | 3.2% |
| Hispanic | 2.9% | 0.3% | 18.4% |
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| Marriage & Family | | | |
| | South Portland, ME | Southwest Harbor, ME | United States |
| Married Population | 43.7% | 58.3% | 49.8% |
| Currently Married | 43.2% | 57.0% | 48.0% |
| Married but Separated | 0.5% | 1.3% | 1.8% |
| Single Population | 56.3% | 41.7% | 50.2% |
| Never Married | 35.6% | 21.2% | 33.8% |
| Divorced | 14.8% | 12.1% | 10.8% |
| Widowed | 5.9% | 8.4% | 5.6% |
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| Household Size | 2.21 | 2.13 | 2.60 |
| Households | 11,672 | 708 | 124,010,992 |
| Family Households | 6,497 | 391 | 80,755,759 |
| Married couple, w/children | 26.0% | 28.1% | 30.5% |
| Married couple, no children | 49.4% | 62.4% | 42.9% |
| Non Family Households | 5,175 | 317 | 43,255,233 |
| Single householder, w/children | 10.1% | 1.0% | 15.8% |
| Single householder, no children | 14.5% | 8.4% | 10.8% |