Union City is a city in Wayne Township, Randolph County, Indiana, United States. As of the 2020 census, the city had a population of 3,454. Union City was a stop along the Pittsburgh, Cincinnati, Chicago and St. Louis Railroad, a forerunner of the Pennsylvania Railroad that connected Pittsburgh to Chicago and St. Louis. The Cleveland, Cincinnati, Chicago and St. Louis Railway had the east–west route connecting Indianapolis, Anderson and Muncie, Indiana with Sidney, Bellefontaine and Columbus, Ohio.