Founded in 1850, Union County is one of 95 counties in the state of Tennessee. Historically, Union County was formed from Grainger, Claiborne, Campbell, Anderson and Knox counties. The city of Maynardville is the county seat. With FIPS code of 173, Union County has a population of 20,040 and area of 224 square miles (580 km2).
List of all cities in Union County, TN alphabetically
| City/Town | Postal Code | Area Code |
| Luttrell, TN | 37779 | 865 |
| Maynardville, TN | 37807 | 865 |
| Sharps Chapel, TN | 37866 | 865 |