The Lake Traverse Indian Reservation is the homeland of the Sisseton Wahpeton Oyate, a branch of the Santee Dakota group of Native Americans. The reservation is located in parts of five counties in extreme northeastern South Dakota and parts of two counties in southeastern North Dakota, USA. Over 60 percent of its land area lies in Roberts County, South Dakota, but there are lesser amounts in Marshall, Day, Grant, and Codington counties in South Dakota, as well as Sargent and Richland counties in North Dakota. Its resident population of 10,408 persons was counted during the 2000 census. About one-third of its inhabitants claim to be of solely Native American heritage.