| | Portland, TX | Myrtle Beach, SC | United States |
| Population | 19,914 | 35,116 | 329,725,481 |
| Female Population | 47.8% | 51.6% | 50.5% |
| Male Population | 52.2% | 48.4% | 49.5% |
| Median Age | 33.7 | 45.7 | 38.4 |
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| Population - 2010 | 16,160 | 27,034 | 309,327,143 |
| Population - 2000 | 14,827 | 22,759 | 285,036,114 |
| Population - 1990 | 12,224 | 24,848 | 251,960,433 |
| Pop. 2000 to Now | 19.8% | 56.2% | 15.6% |
| Pop. 1990 to Now | 45.4% | 43.1% | 30.8% |
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| Population Density | 1,788.1 | 1,487.2 | 93.4 |
| Land Area | 11.1 | 23.6 | 3,531,905.4 |
| Water Area | 2.7 | 0.3 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Portland, TX | Myrtle Beach, SC | United States |
| Age 0 to 4 | 6.8% | 5.7% | 5.9% |
| Age 5 to 9 | 8.4% | 4.0% | 6.1% |
| Age 10 to 14 | 8.0% | 5.9% | 6.6% |
| Age 15 to 17 | 3.3% | 2.9% | 3.9% |
| Age 18 to 20 | 4.2% | 2.1% | 4.0% |
| Age 21 to 24 | 5.3% | 3.8% | 5.2% |
| Age 25 to 34 | 16.1% | 12.9% | 13.8% |
| Age 35 to 44 | 15.0% | 11.5% | 12.9% |
| Age 45 to 54 | 10.5% | 13.2% | 12.6% |
| Age 55 to 59 | 4.5% | 8.2% | 6.7% |
| Age 60 to 64 | 4.7% | 8.4% | 6.3% |
| Age 65 to 74 | 8.0% | 14.3% | 9.6% |
| Age 75 to 84 | 3.5% | 5.2% | 4.5% |
| Age 85 and over | 1.9% | 1.8% | 1.9% |
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| Race | | | |
| | Portland, TX | Myrtle Beach, SC | United States |
| White | 51.6% | 65.2% | 59.4% |
| Black | 2.1% | 17.3% | 12.2% |
| Asian | 2.0% | 1.2% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.4% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.8% | 2.9% | 3.2% |
| Hispanic | 42.0% | 13.3% | 18.4% |
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| Marriage & Family | | | |
| | Portland, TX | Myrtle Beach, SC | United States |
| Married Population | 54.3% | 47.7% | 49.8% |
| Currently Married | 53.2% | 45.7% | 48.0% |
| Married but Separated | 1.0% | 1.9% | 1.8% |
| Single Population | 45.7% | 52.3% | 50.2% |
| Never Married | 29.6% | 32.6% | 33.8% |
| Divorced | 10.8% | 12.7% | 10.8% |
| Widowed | 5.3% | 6.9% | 5.6% |
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| Household Size | 2.89 | 2.33 | 2.60 |
| Households | 6,869 | 15,025 | 124,010,992 |
| Family Households | 5,174 | 8,535 | 80,755,759 |
| Married couple, w/children | 32.2% | 23.1% | 30.5% |
| Married couple, no children | 41.1% | 51.3% | 42.9% |
| Non Family Households | 1,695 | 6,490 | 43,255,233 |
| Single householder, w/children | 18.2% | 14.4% | 15.8% |
| Single householder, no children | 8.5% | 11.2% | 10.8% |