Cottage Hills is an unincorporated community in Madison County, Illinois, United States. In 2018, the Cottage Hills ZIP Code area served a population of 3,604. Cottage Hills is west of Bethalto, north of Rosewood Heights, east of East Alton, and is a part of the Greater St. Louis. Cottage Hills has a post office with ZIP Code 62018. Between 1915 and 198…Cottage Hills is an unincorporated community in Madison County, Illinois, United States. In 2018, the Cottage Hills ZIP Code area served a population of 3,604. Cottage Hills is west of Bethalto, north of Rosewood Heights, east of East Alton, and is a part of the Greater St. Louis. Cottage Hills has a post office with ZIP Code 62018. Between 1915 and 1980 a railway under the name of St. Louis Division Old Line used to pass through the community. Similar to most communities in Madison County, Cottage Hills is a bedroom community.