Turtle Mountain Indian Reservation (Ojibwe language: Mikinaakwajiwing) is an Indian Reservation located primarily in northern North Dakota, United States. It is the land base for the Turtle Mountain Band of Chippewa Indians (part of the large family of Ojibwe peoples).
The Turtle Mountain Indian Reservation was established by Presidential Executive Order on December 21, 1882. The main reservation lies in the northern part of Rolette County, North Dakota and has a land area of 67.583 square miles (175.04 km2) and a 2000 census population of 5,815 persons. It also has extensive off-reservation trust lands, which make the reservation's lands the most widely dispersed of all reservations in the nation.
These lands are spread across 22 counties in three states: North Dakota, Montana and South Dakota. Including these lands, the reservation's land area is a total of 233.036 square miles (603.56 km2). Its total resident population at the 2000 census was 8,331.
The largest portion of off-reservation trust land is located in Rolette County, with significant parcels in Phillips, Blaine, Sheridan and Roosevelt counties in Montana; and in Williams County, North Dakota. Sixteen other counties have lesser amounts of trust land.
The Reservation is situated in the southeastern part of the Turtle Mountain Plateau. The Turtle Mountain Plateau covers a large area in extreme northern North Dakota and extreme southern Manitoba. In the United States, the plateau is not as extensively covered by a forest as in the Canadian part of the plateau. The forest which covers the plateau, is clear evidence that the boreal forest extended much further westward. The Turtle Mountains are not really mountains but tiny hills, and the plateau is considered an extension of the plains or prairie. It is only slightly higher in elevation, about 500 feet or more. Many lakes dot the plateau, which is evidence that the area was covered by a large lake in ancient times.