Bennett County, South Dakota: History
This land has for centuries been the traditional territory of the Oglala Lakota, also known as the Sioux; it has been part of their legally defined territory since the treaty of 1851 and has remained within its legal boundaries through various other Treaties and Acts that reduced their land base to the current boundaries of the Pine Ridge Indian Reservation when the reservation was created by the Act of March 2, 1889 (25 Stat. 888). Despite its reservation status, most of the county was opened for settlement by the Act of May 27, 1910, where the US Congress "authorized and directed the Secretary of Interior to sell and dispose of all that portion of the Pine Ridge Indian Reservation, in the State of South Dakota, lying and being in Bennett County". Open settlement was ended by a Secretarial Order of June 10, 1936, which restored "to tribal ownership of all lands which are now, or may hereafter be, classified as undisposed-of surplus opened lands of the Pine Ridge Reservation...." The allotment process left the county's landownership a "checkerboard" mixture of Indian trust lands and state and private lands.
The county was created in 1909, with land partitioned from Fall River County. On April 27, 1912, the county's first board of commissioners was elected. In November 1912, residents chose the town of Martin as the county seat.