| | Portland, TN | Earlham, IA | United States |
| Population | 13,031 | 1,343 | 329,725,481 |
| Female Population | 49.9% | 49.8% | 50.5% |
| Male Population | 50.2% | 50.2% | 49.5% |
| Median Age | 33.3 | 41.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 11,530 | 1,447 | 309,327,143 |
| Population - 2000 | 8,458 | 1,298 | 285,036,114 |
| Population - 1990 | 5,165 | 1,157 | 251,960,433 |
| Pop. 2000 to Now | 57.3% | 8.6% | 15.6% |
| Pop. 1990 to Now | 157.5% | 21.8% | 30.8% |
| space4 | | | |
| Population Density | 977.1 | 1,388.8 | 93.4 |
| Land Area | 13.3 | 1.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Portland, TN | Earlham, IA | United States |
| Age 0 to 4 | 6.8% | 4.5% | 5.9% |
| Age 5 to 9 | 7.5% | 6.4% | 6.1% |
| Age 10 to 14 | 6.5% | 7.7% | 6.6% |
| Age 15 to 17 | 6.5% | 5.6% | 3.9% |
| Age 18 to 20 | 5.4% | 6.2% | 4.0% |
| Age 21 to 24 | 5.6% | 2.5% | 5.2% |
| Age 25 to 34 | 14.2% | 10.4% | 13.8% |
| Age 35 to 44 | 14.0% | 11.8% | 12.9% |
| Age 45 to 54 | 12.9% | 20.4% | 12.6% |
| Age 55 to 59 | 4.9% | 5.7% | 6.7% |
| Age 60 to 64 | 5.8% | 4.5% | 6.3% |
| Age 65 to 74 | 7.2% | 10.4% | 9.6% |
| Age 75 to 84 | 1.9% | 2.9% | 4.5% |
| Age 85 and over | 0.8% | 1.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Portland, TN | Earlham, IA | United States |
| White | 86.9% | 96.8% | 59.4% |
| Black | 2.1% | 0.1% | 12.2% |
| Asian | 0.2% | 0.0% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 1.3% | 3.1% | 3.2% |
| Hispanic | 9.1% | 0.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Portland, TN | Earlham, IA | United States |
| Married Population | 49.5% | 63.8% | 49.8% |
| Currently Married | 46.4% | 62.9% | 48.0% |
| Married but Separated | 3.2% | 0.9% | 1.8% |
| Single Population | 50.5% | 36.2% | 50.2% |
| Never Married | 31.0% | 23.3% | 33.8% |
| Divorced | 15.1% | 8.4% | 10.8% |
| Widowed | 4.4% | 4.5% | 5.6% |
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| Household Size | 2.77 | 2.62 | 2.60 |
| Households | 4,688 | 512 | 124,010,992 |
| Family Households | 3,330 | 371 | 80,755,759 |
| Married couple, w/children | 38.2% | 44.2% | 30.5% |
| Married couple, no children | 30.9% | 43.4% | 42.9% |
| Non Family Households | 1,358 | 141 | 43,255,233 |
| Single householder, w/children | 22.8% | 11.1% | 15.8% |
| Single householder, no children | 8.1% | 1.3% | 10.8% |