In pre-colonial times, the land now occupied by Aroostook County was inhabited by the Micmacs and the Maliseets, bands of which still reside in the area.
French explorers, led by Samuel de Champlain and Sieur de Monts, first visited the area in 1604, but the area was not settled until much later.
The first settlers arrived in the Aroostook River area during a border dispute between the United States and Great Britain. They settled on property claimed by both sides.
Even within the United States, the boundaries were anything but settled. Although Maine was admitted to the Union in 1820, a large part of what was to become Aroostook County still belonged to Massachusetts.