| | Lancaster, KY | Arlington, TN | United States |
| Population | 3,845 | 14,158 | 329,725,481 |
| Female Population | 56.4% | 51.3% | 50.5% |
| Male Population | 43.6% | 48.7% | 49.5% |
| Median Age | 36.2 | 35.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,792 | 11,522 | 309,327,143 |
| Population - 2000 | 3,734 | 2,569 | 285,036,114 |
| Population - 1990 | 3,421 | 1,541 | 251,960,433 |
| Pop. 2000 to Now | 2.8% | 357.3% | 15.6% |
| Pop. 1990 to Now | 12.3% | 662.4% | 30.8% |
| space4 | | | |
| Population Density | 1,758.1 | 615.2 | 93.4 |
| Land Area | 2.2 | 23.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Lancaster, KY | Arlington, TN | United States |
| Age 0 to 4 | 7.0% | 6.7% | 5.9% |
| Age 5 to 9 | 7.2% | 7.5% | 6.1% |
| Age 10 to 14 | 7.8% | 12.7% | 6.6% |
| Age 15 to 17 | 3.8% | 5.9% | 3.9% |
| Age 18 to 20 | 4.2% | 4.4% | 4.0% |
| Age 21 to 24 | 2.5% | 3.4% | 5.2% |
| Age 25 to 34 | 16.3% | 9.2% | 13.8% |
| Age 35 to 44 | 11.1% | 17.5% | 12.9% |
| Age 45 to 54 | 13.7% | 14.9% | 12.6% |
| Age 55 to 59 | 5.2% | 6.0% | 6.7% |
| Age 60 to 64 | 4.7% | 4.2% | 6.3% |
| Age 65 to 74 | 5.7% | 5.6% | 9.6% |
| Age 75 to 84 | 7.5% | 1.5% | 4.5% |
| Age 85 and over | 3.3% | 0.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Lancaster, KY | Arlington, TN | United States |
| White | 87.3% | 76.8% | 59.4% |
| Black | 9.2% | 16.6% | 12.2% |
| Asian | 0.0% | 0.4% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.0% | 0.4% |
| Two or More Races | 1.4% | 3.6% | 3.2% |
| Hispanic | 1.9% | 2.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Lancaster, KY | Arlington, TN | United States |
| Married Population | 49.5% | 62.6% | 49.8% |
| Currently Married | 44.2% | 62.3% | 48.0% |
| Married but Separated | 5.4% | 0.4% | 1.8% |
| Single Population | 50.5% | 37.4% | 50.2% |
| Never Married | 29.4% | 24.2% | 33.8% |
| Divorced | 13.1% | 8.1% | 10.8% |
| Widowed | 8.0% | 5.0% | 5.6% |
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| Household Size | 2.54 | 3.23 | 2.60 |
| Households | 1,479 | 4,383 | 124,010,992 |
| Family Households | 1,059 | 3,763 | 80,755,759 |
| Married couple, w/children | 20.8% | 49.5% | 30.5% |
| Married couple, no children | 30.5% | 32.6% | 42.9% |
| Non Family Households | 420 | 620 | 43,255,233 |
| Single householder, w/children | 34.4% | 14.3% | 15.8% |
| Single householder, no children | 14.4% | 3.5% | 10.8% |