Miami is a city in Saline County, Missouri, United States. The population was 175 at the 2010 census. Miami was originally called Greenville, …Miami is a city in Saline County, Missouri, United States. The population was 175 at the 2010 census. Miami was originally called Greenville, under which name it was platted in 1838. A post office called Miami has been in operation since 1838. The present name is after the Miami Indians.