| | Mount Airy, MD | Knoxville, TN | United States |
| Population | 9,621 | 189,339 | 329,725,481 |
| Female Population | 51.7% | 51.7% | 50.5% |
| Male Population | 48.4% | 48.3% | 49.5% |
| Median Age | 38.9 | 33.5 | 38.4 |
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| Population - 2010 | 9,300 | 178,269 | 309,327,143 |
| Population - 2000 | 6,425 | 173,890 | 285,036,114 |
| Population - 1990 | 3,730 | 165,121 | 251,960,433 |
| Pop. 2000 to Now | 47.9% | 9.4% | 15.6% |
| Pop. 1990 to Now | 154.8% | 15.2% | 30.8% |
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| Population Density | 2,336.3 | 1,918.1 | 93.4 |
| Land Area | 4.1 | 98.7 | 3,531,905.4 |
| Water Area | 0.0 | 5.5 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Mount Airy, MD | Knoxville, TN | United States |
| Age 0 to 4 | 7.1% | 5.3% | 5.9% |
| Age 5 to 9 | 8.9% | 5.5% | 6.1% |
| Age 10 to 14 | 5.6% | 4.9% | 6.6% |
| Age 15 to 17 | 5.2% | 3.2% | 3.9% |
| Age 18 to 20 | 2.6% | 7.1% | 4.0% |
| Age 21 to 24 | 4.2% | 9.9% | 5.2% |
| Age 25 to 34 | 11.3% | 15.9% | 13.8% |
| Age 35 to 44 | 14.0% | 11.9% | 12.9% |
| Age 45 to 54 | 16.2% | 11.1% | 12.6% |
| Age 55 to 59 | 6.9% | 6.0% | 6.7% |
| Age 60 to 64 | 5.8% | 5.2% | 6.3% |
| Age 65 to 74 | 5.8% | 8.3% | 9.6% |
| Age 75 to 84 | 5.0% | 3.9% | 4.5% |
| Age 85 and over | 1.4% | 1.7% | 1.9% |
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| Race | | | |
| | Mount Airy, MD | Knoxville, TN | United States |
| White | 82.6% | 72.1% | 59.4% |
| Black | 3.4% | 16.3% | 12.2% |
| Asian | 1.9% | 1.7% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.4% | 0.4% |
| Two or More Races | 4.4% | 3.8% | 3.2% |
| Hispanic | 7.7% | 5.7% | 18.4% |
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| Marriage & Family | | | |
| | Mount Airy, MD | Knoxville, TN | United States |
| Married Population | 65.1% | 36.7% | 49.8% |
| Currently Married | 64.1% | 34.5% | 48.0% |
| Married but Separated | 1.0% | 2.2% | 1.8% |
| Single Population | 34.9% | 63.3% | 50.2% |
| Never Married | 23.9% | 43.4% | 33.8% |
| Divorced | 5.9% | 13.8% | 10.8% |
| Widowed | 5.1% | 6.1% | 5.6% |
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| Household Size | 2.95 | 2.19 | 2.60 |
| Households | 3,237 | 82,586 | 124,010,992 |
| Family Households | 2,586 | 39,549 | 80,755,759 |
| Married couple, w/children | 44.0% | 25.1% | 30.5% |
| Married couple, no children | 45.2% | 38.6% | 42.9% |
| Non Family Households | 651 | 43,037 | 43,255,233 |
| Single householder, w/children | 7.2% | 23.9% | 15.8% |
| Single householder, no children | 3.6% | 12.5% | 10.8% |