Hampden is a town on the Penobscot River estuary in Penobscot County, Maine, United States. The population was 7,709 at the 2020 census. Hampden is part of the Bangor metropolitan statistical ar…Hampden is a town on the Penobscot River estuary in Penobscot County, Maine, United States. The population was 7,709 at the 2020 census. Hampden is part of the Bangor metropolitan statistical area.