| | St. Matthews, KY | Chattanooga, TN | United States |
| Population | 17,588 | 180,353 | 329,725,481 |
| Female Population | 52.0% | 52.5% | 50.5% |
| Male Population | 48.0% | 47.5% | 49.5% |
| Median Age | 38 | 36.7 | 38.4 |
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| Population - 2010 | 17,460 | 170,582 | 309,327,143 |
| Population - 2000 | 15,852 | 155,554 | 285,036,114 |
| Population - 1990 | 15,800 | 152,466 | 251,960,433 |
| Pop. 2000 to Now | 13.5% | 18.8% | 15.6% |
| Pop. 1990 to Now | 13.8% | 21.2% | 30.8% |
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| Population Density | 4,019.2 | 1,261.9 | 93.4 |
| Land Area | 4.4 | 142.9 | 3,531,905.4 |
| Water Area | 0.0 | 7.7 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | St. Matthews, KY | Chattanooga, TN | United States |
| Age 0 to 4 | 4.9% | 6.2% | 5.9% |
| Age 5 to 9 | 3.4% | 5.2% | 6.1% |
| Age 10 to 14 | 3.6% | 5.5% | 6.6% |
| Age 15 to 17 | 2.0% | 3.1% | 3.9% |
| Age 18 to 20 | 2.3% | 4.9% | 4.0% |
| Age 21 to 24 | 5.1% | 5.8% | 5.2% |
| Age 25 to 34 | 24.0% | 16.8% | 13.8% |
| Age 35 to 44 | 12.2% | 12.2% | 12.9% |
| Age 45 to 54 | 10.8% | 10.7% | 12.6% |
| Age 55 to 59 | 6.4% | 6.0% | 6.7% |
| Age 60 to 64 | 5.2% | 6.9% | 6.3% |
| Age 65 to 74 | 10.7% | 10.1% | 9.6% |
| Age 75 to 84 | 5.7% | 4.5% | 4.5% |
| Age 85 and over | 3.8% | 2.1% | 1.9% |
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| Race | | | |
| | St. Matthews, KY | Chattanooga, TN | United States |
| White | 86.5% | 56.3% | 59.4% |
| Black | 5.4% | 30.3% | 12.2% |
| Asian | 2.9% | 2.7% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.3% | 0.3% | 0.4% |
| Two or More Races | 1.7% | 3.1% | 3.2% |
| Hispanic | 3.1% | 7.3% | 18.4% |
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| Marriage & Family | | | |
| | St. Matthews, KY | Chattanooga, TN | United States |
| Married Population | 45.9% | 39.6% | 49.8% |
| Currently Married | 44.3% | 37.3% | 48.0% |
| Married but Separated | 1.6% | 2.3% | 1.8% |
| Single Population | 54.1% | 60.4% | 50.2% |
| Never Married | 33.4% | 39.4% | 33.8% |
| Divorced | 14.5% | 13.7% | 10.8% |
| Widowed | 6.2% | 7.2% | 5.6% |
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| Household Size | 1.97 | 2.25 | 2.60 |
| Households | 8,802 | 76,508 | 124,010,992 |
| Family Households | 4,214 | 40,213 | 80,755,759 |
| Married couple, w/children | 22.3% | 22.9% | 30.5% |
| Married couple, no children | 52.9% | 40.7% | 42.9% |
| Non Family Households | 4,588 | 36,295 | 43,255,233 |
| Single householder, w/children | 12.8% | 21.2% | 15.8% |
| Single householder, no children | 11.9% | 15.3% | 10.8% |