Columbus City is a city in western Louisa County, Iowa, United States. The population was 392 at the 2020 census. It is part of the Muscatine Mi…Columbus City is a city in western Louisa County, Iowa, United States. The population was 392 at the 2020 census. It is part of the Muscatine Micropolitan Statistical Area. Columbus City was platted in the 1840s.