| | Watertown, TN | Smyrna, TN | United States |
| Population | 1,812 | 52,401 | 329,725,481 |
| Female Population | 54.8% | 50.6% | 50.5% |
| Male Population | 45.2% | 49.4% | 49.5% |
| Median Age | 39 | 34.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,476 | 40,589 | 309,327,143 |
| Population - 2000 | 1,358 | 25,569 | 285,036,114 |
| Population - 1990 | 1,250 | 13,647 | 251,960,433 |
| Pop. 2000 to Now | 13.1% | 108.0% | 15.6% |
| Pop. 1990 to Now | 22.9% | 289.7% | 30.8% |
| space4 | | | |
| Population Density | 1,363.4 | 1,729.0 | 93.4 |
| Land Area | 1.3 | 30.3 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Watertown, TN | Smyrna, TN | United States |
| Age 0 to 4 | 6.5% | 7.6% | 5.9% |
| Age 5 to 9 | 5.8% | 7.3% | 6.1% |
| Age 10 to 14 | 10.2% | 6.8% | 6.6% |
| Age 15 to 17 | 2.8% | 3.5% | 3.9% |
| Age 18 to 20 | 2.2% | 4.2% | 4.0% |
| Age 21 to 24 | 4.5% | 5.3% | 5.2% |
| Age 25 to 34 | 12.7% | 16.3% | 13.8% |
| Age 35 to 44 | 13.5% | 14.9% | 12.9% |
| Age 45 to 54 | 9.9% | 13.0% | 12.6% |
| Age 55 to 59 | 6.7% | 6.4% | 6.7% |
| Age 60 to 64 | 7.9% | 5.1% | 6.3% |
| Age 65 to 74 | 11.0% | 5.9% | 9.6% |
| Age 75 to 84 | 5.4% | 3.0% | 4.5% |
| Age 85 and over | 0.9% | 0.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Watertown, TN | Smyrna, TN | United States |
| White | 78.3% | 61.6% | 59.4% |
| Black | 11.3% | 17.0% | 12.2% |
| Asian | 0.0% | 5.0% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 4.4% | 0.3% | 0.4% |
| Two or More Races | 2.3% | 3.6% | 3.2% |
| Hispanic | 3.7% | 12.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Watertown, TN | Smyrna, TN | United States |
| Married Population | 53.1% | 48.3% | 49.8% |
| Currently Married | 50.9% | 47.2% | 48.0% |
| Married but Separated | 2.1% | 1.1% | 1.8% |
| Single Population | 46.9% | 51.7% | 50.2% |
| Never Married | 23.1% | 34.2% | 33.8% |
| Divorced | 13.6% | 11.6% | 10.8% |
| Widowed | 10.2% | 5.9% | 5.6% |
| space5 | | | |
| Household Size | 2.57 | 2.74 | 2.60 |
| Households | 706 | 19,022 | 124,010,992 |
| Family Households | 513 | 13,173 | 80,755,759 |
| Married couple, w/children | 27.9% | 31.5% | 30.5% |
| Married couple, no children | 38.0% | 36.2% | 42.9% |
| Non Family Households | 193 | 5,849 | 43,255,233 |
| Single householder, w/children | 22.6% | 20.4% | 15.8% |
| Single householder, no children | 11.5% | 12.0% | 10.8% |