| | Grosse Ile, MI | Germantown, TN | United States |
| Population | 10,682 | 40,955 | 329,725,481 |
| Female Population | 52.8% | 50.6% | 50.5% |
| Male Population | 47.3% | 49.4% | 49.5% |
| Median Age | 52.2 | 43.7 | 38.4 |
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| Population - 2010 | 10,347 | 38,877 | 309,327,143 |
| Population - 2000 | 10,894 | 37,348 | 285,036,114 |
| Population - 1990 | 9,781 | 32,893 | 251,960,433 |
| Pop. 2000 to Now | -7.3% | 4.9% | 15.6% |
| Pop. 1990 to Now | 3.3% | 19.1% | 30.8% |
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| Population Density | 1,158.1 | 2,049.2 | 93.4 |
| Land Area | 9.2 | 20.0 | 3,531,905.4 |
| Water Area | 9.4 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Grosse Ile, MI | Germantown, TN | United States |
| Age 0 to 4 | 5.4% | 5.7% | 5.9% |
| Age 5 to 9 | 4.7% | 8.9% | 6.1% |
| Age 10 to 14 | 4.8% | 7.5% | 6.6% |
| Age 15 to 17 | 4.2% | 4.4% | 3.9% |
| Age 18 to 20 | 3.2% | 2.4% | 4.0% |
| Age 21 to 24 | 1.7% | 2.3% | 5.2% |
| Age 25 to 34 | 7.1% | 6.7% | 13.8% |
| Age 35 to 44 | 10.2% | 14.6% | 12.9% |
| Age 45 to 54 | 12.5% | 13.7% | 12.6% |
| Age 55 to 59 | 9.9% | 7.1% | 6.7% |
| Age 60 to 64 | 8.0% | 5.6% | 6.3% |
| Age 65 to 74 | 17.0% | 11.9% | 9.6% |
| Age 75 to 84 | 8.6% | 6.4% | 4.5% |
| Age 85 and over | 2.6% | 3.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Grosse Ile, MI | Germantown, TN | United States |
| White | 92.7% | 85.9% | 59.4% |
| Black | 0.7% | 3.4% | 12.2% |
| Asian | 2.9% | 5.8% | 5.6% |
| Native American | 0.2% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 1.8% | 1.3% | 3.2% |
| Hispanic | 1.6% | 3.2% | 18.4% |
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| Marriage & Family | | | |
| | Grosse Ile, MI | Germantown, TN | United States |
| Married Population | 64.4% | 71.4% | 49.8% |
| Currently Married | 64.1% | 70.4% | 48.0% |
| Married but Separated | 0.3% | 1.0% | 1.8% |
| Single Population | 35.6% | 28.6% | 50.2% |
| Never Married | 20.1% | 16.2% | 33.8% |
| Divorced | 9.7% | 6.1% | 10.8% |
| Widowed | 5.8% | 6.3% | 5.6% |
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| Household Size | 2.51 | 2.66 | 2.60 |
| Households | 4,241 | 15,358 | 124,010,992 |
| Family Households | 3,194 | 11,850 | 80,755,759 |
| Married couple, w/children | 29.2% | 41.1% | 30.5% |
| Married couple, no children | 60.9% | 50.6% | 42.9% |
| Non Family Households | 1,047 | 3,508 | 43,255,233 |
| Single householder, w/children | 4.9% | 5.2% | 15.8% |
| Single householder, no children | 5.1% | 3.1% | 10.8% |