Unicoi County is a county located in the U.S. state of Tennessee. As of the 2020 census, the population was 17,928. Its county seat is Erwin. Unicoi is a Cherokee word meaning "white," "hazy," "fog-like," or "fog draped," and refers to the mist often seen in the foothills and mountains of this far northeast county. Unicoi County is part of the Johnson City Metropolitan Statistical Area, which is a component of the Johnson City–Kingsport–Bristol, TN-VA Combined Statistical Area, commonly known as the "Tri-Cities" region.

Johnson City is a city in Washington, Carter, and Sullivan counties in the U.S. state of Tennessee, mostly in Washington County. As of the 2020 United States census, the population was 71,046, making it the eighth largest city in Tennessee. Johnson City is the principal city of the Johnson City Metropolitan Statistical Area, which consists of Carter, Unicoi, and Washington counties and had a population of 207,285 as of 2020. The MSA is also a component of the Tri-Cities region. This CSA is the fifth-largest in Tennessee, with a population of 514,899 as of 2020.