Colona is a city in Henry County, Illinois, along the Green River. It is part of the Quad Cities metropolitan area. The population was 5,045 at the 2…Colona is a city in Henry County, Illinois, along the Green River. It is part of the Quad Cities metropolitan area. The population was 5,045 at the 2020 Census. The City of Colona was created in 1997 by the merger of the former City of Green Rock and the former Village of Colona. It was the first community in Illinois to merge by popular vote.