Piscataquis County is a county located in the U.S. state of Maine. As of the 2020 census, its population was 16,800, making it Maine's least-populous county. Its county seat is Dover-Foxcroft. The county was incorporated on March 23, 1838, taken from the western part of Penobscot County and the eastern part of Somerset County. It is named for an Abenaki word meaning "branch of the river" or "at the river branch."