The Fort Belknap Indian Reservation in central Montana is home to two tribes: the Assiniboine and the Gros Ventre. The 675,000-acre reservation consists primarily of rolling prairie, with bottomlands along the Milk River, which forms the northern border of the reservation. The Little Rocky Mountains cover the southern quarter of the reservation. It is a sparse, hardscrabble landscape where rainfall is unpredictable, and the wind blows furnace-hot in the summer and has an arctic bent in the winter. It is a difficult place to support a modern economy but perfect country for buffalo, which is what drew the Assiniboine and Gros Ventre to this region.

Nearly all of the Fort Belknap Reservation is in Blaine County, which was organized in 1912. Approximately a third of the county's residents are Indians. Unlike the Blackfeet farther west or the Sioux to the east, these two tribes never engaged in warfare with the incoming settlers. Early on they decided to try to get along with the newcomers rather than fight them, perhaps in the hope of receiving better treatment.

Since 1927, Blaine County had used an at-large voting system to elect three commissioners; each commissioner represented a residential district but was elected at-large by all voters in the county. The commissioners served six-year terms, which were staggered so that only one commissioner was chosen every two years. Until the U.S. v. Blaine County case was litigated, no Indian had ever been elected to the county commission.