| | Spencer, TN | Carthage, TN | United States |
| Population | 1,531 | 2,529 | 329,725,481 |
| Female Population | 54.4% | 54.1% | 50.5% |
| Male Population | 45.6% | 45.9% | 49.5% |
| Median Age | 48.3 | 37.5 | 38.4 |
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| Population - 2010 | 1,611 | 2,295 | 309,327,143 |
| Population - 2000 | 1,713 | 2,251 | 285,036,114 |
| Population - 1990 | 1,125 | 2,386 | 251,960,433 |
| Pop. 2000 to Now | -0.2% | 3.6% | 15.6% |
| Pop. 1990 to Now | 52.0% | -2.3% | 30.8% |
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| Population Density | 233.6 | 871.5 | 93.4 |
| Land Area | 6.6 | 2.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Spencer, TN | Carthage, TN | United States |
| Age 0 to 4 | 2.8% | 8.8% | 5.9% |
| Age 5 to 9 | 4.7% | 4.6% | 6.1% |
| Age 10 to 14 | 5.4% | 3.2% | 6.6% |
| Age 15 to 17 | 4.3% | 4.1% | 3.9% |
| Age 18 to 20 | 2.2% | 3.8% | 4.0% |
| Age 21 to 24 | 2.4% | 6.4% | 5.2% |
| Age 25 to 34 | 10.8% | 14.0% | 13.8% |
| Age 35 to 44 | 9.3% | 12.2% | 12.9% |
| Age 45 to 54 | 18.9% | 10.5% | 12.6% |
| Age 55 to 59 | 6.5% | 5.4% | 6.7% |
| Age 60 to 64 | 7.9% | 7.8% | 6.3% |
| Age 65 to 74 | 15.5% | 10.6% | 9.6% |
| Age 75 to 84 | 7.6% | 5.3% | 4.5% |
| Age 85 and over | 1.7% | 3.2% | 1.9% |
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| Race | | | |
| | Spencer, TN | Carthage, TN | United States |
| White | 94.4% | 83.7% | 59.4% |
| Black | 0.5% | 6.3% | 12.2% |
| Asian | 0.0% | 1.1% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 4.9% | 4.2% | 3.2% |
| Hispanic | 0.2% | 4.7% | 18.4% |
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| Marriage & Family | | | |
| | Spencer, TN | Carthage, TN | United States |
| Married Population | 46.0% | 39.1% | 49.8% |
| Currently Married | 41.2% | 35.7% | 48.0% |
| Married but Separated | 4.8% | 3.4% | 1.8% |
| Single Population | 54.0% | 60.9% | 50.2% |
| Never Married | 22.1% | 29.3% | 33.8% |
| Divorced | 19.8% | 22.6% | 10.8% |
| Widowed | 12.2% | 9.1% | 5.6% |
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| Household Size | 2.32 | 2.44 | 2.60 |
| Households | 615 | 962 | 124,010,992 |
| Family Households | 418 | 555 | 80,755,759 |
| Married couple, w/children | 21.8% | 19.1% | 30.5% |
| Married couple, no children | 44.7% | 43.2% | 42.9% |
| Non Family Households | 197 | 407 | 43,255,233 |
| Single householder, w/children | 16.3% | 28.5% | 15.8% |
| Single householder, no children | 17.2% | 9.2% | 10.8% |