| | Marne, IA | Phoenixville, PA | United States |
| Population | 118 | 18,437 | 329,725,481 |
| Female Population | 44.9% | 45.2% | 50.5% |
| Male Population | 55.1% | 54.8% | 49.5% |
| Median Age | 50.5 | 34.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 120 | 16,475 | 309,327,143 |
| Population - 2000 | 149 | 14,788 | 285,036,114 |
| Population - 1990 | 149 | 15,066 | 251,960,433 |
| Pop. 2000 to Now | -23.5% | 14.4% | 15.6% |
| Pop. 1990 to Now | -23.5% | 12.2% | 30.8% |
| space4 | | | |
| Population Density | 205.2 | 5,252.7 | 93.4 |
| Land Area | 0.6 | 3.5 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Marne, IA | Phoenixville, PA | United States |
| Age 0 to 4 | 1.7% | 6.6% | 5.9% |
| Age 5 to 9 | 3.4% | 5.0% | 6.1% |
| Age 10 to 14 | 7.6% | 5.6% | 6.6% |
| Age 15 to 17 | 6.8% | 2.7% | 3.9% |
| Age 18 to 20 | 0.0% | 1.4% | 4.0% |
| Age 21 to 24 | 7.6% | 6.4% | 5.2% |
| Age 25 to 34 | 4.2% | 23.9% | 13.8% |
| Age 35 to 44 | 0.8% | 15.6% | 12.9% |
| Age 45 to 54 | 27.1% | 10.4% | 12.6% |
| Age 55 to 59 | 16.9% | 6.3% | 6.7% |
| Age 60 to 64 | 16.9% | 5.0% | 6.3% |
| Age 65 to 74 | 2.5% | 6.6% | 9.6% |
| Age 75 to 84 | 3.4% | 4.0% | 4.5% |
| Age 85 and over | 0.8% | 0.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Marne, IA | Phoenixville, PA | United States |
| White | 100.0% | 81.6% | 59.4% |
| Black | 0.0% | 7.2% | 12.2% |
| Asian | 0.0% | 3.2% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 0.0% | 3.4% | 3.2% |
| Hispanic | 0.0% | 4.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Marne, IA | Phoenixville, PA | United States |
| Married Population | 53.4% | 40.2% | 49.8% |
| Currently Married | 53.4% | 37.9% | 48.0% |
| Married but Separated | 0.0% | 2.3% | 1.8% |
| Single Population | 46.6% | 59.8% | 50.2% |
| Never Married | 25.2% | 43.7% | 33.8% |
| Divorced | 15.5% | 11.5% | 10.8% |
| Widowed | 5.8% | 4.6% | 5.6% |
| space5 | | | |
| Household Size | 2.03 | 2.32 | 2.60 |
| Households | 58 | 7,897 | 124,010,992 |
| Family Households | 33 | 4,153 | 80,755,759 |
| Married couple, w/children | 12.1% | 30.7% | 30.5% |
| Married couple, no children | 60.6% | 36.3% | 42.9% |
| Non Family Households | 25 | 3,744 | 43,255,233 |
| Single householder, w/children | 6.1% | 18.3% | 15.8% |
| Single householder, no children | 21.2% | 14.8% | 10.8% |