Bluff City is a city in Sullivan County, Tennessee, United States. The population was 1,733 at the 2010 census. It is part of the Kingsport–Bristol (TN)–Bristol (VA) 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.
Bluff City underwent several name changes before incorporating on July 1, 1887 under its present name. The town was originally known as Choate’s Ford, and later took the name Middletown. After the East Tennessee, Virginia and Georgia Railroad was built, crossing the Holston River at the town site, the name Union was adopted. During the Civil War it was called Zollicoffer after Confederate General Felix Zollicoffer, but became Union again at the end of the war and until 1887.