Rainbow City is a city in Etowah County, Alabama, United States. It incorporated in 1950. The population was 9,602 at the 2010 census. I…Rainbow City is a city in Etowah County, Alabama, United States. It incorporated in 1950. The population was 9,602 at the 2010 census. It is part of the Gadsden Metropolitan Statistical Area. This city was named after U.S. Highway 411, called Rainbow Drive, which runs through the middle of the city.