Union City is a city in and the county seat of Obion County, Tennessee, United States. The population was 10,876 at the 2000 census. The name is derived from its location at the junction 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 formerly had a Goodyear Tire Plant. Union City is the principal city of the Union City Micropolitan Area, which includes Obion County and Fulton County, Kentucky.