The Pine Ridge Indian Reservation, also called Pine Ridge Agency, is an Oglala Lakota Indian reservation located in the U.S. state of South Dakota, with a small portion extending into Nebraska. Originally included within the territory of the Great Sioux Reservation, Pine Ridge was created by the Act of March 2, 1889, 25 Stat. 888. in the southwest corner of South Dakota on the Nebraska border. It consists of 3,468.85 mi2 (8,984 km2) of land area and is one of the largest reservations in the United States.