Union City is a city in Obion County, Tennessee, United States. The population was 10,876 at the 2000 census. It is the county seat of Obion County. The name comes from its location at the union of two railroads, one running roughly east-west and the other roughly north-south. Union City is best known for two things: It was the site of a minor battle in the American Civil War in March 1864, and it has a Goodyear Tire Plant. Union City is the principal city of the Union City Micropolitan Statistical Area, which includes Obion County and Fulton County, Kentucky.