Shannon County is a county located in the U.S. state of South Dakota. The population was 13,586 at the 2010 census. Shannon County does not have its own county seat. Instead, Hot Springs in neighboring Fall River County serves as its administrative center. Its largest community is Pine Ridge. The county is named for Peter Shannon, Chief Justice of the Dakota Territory Supreme Court. On November 5, 2014, voters in the county voted by a margin of 2,161 to 526 to rename it Oglala Lakota County; the name change will take effect after a proclamation by the governor, according to state law.
The county is entirely within the Pine Ridge Indian Reservation and contains part of Badlands National Park. It is one of five South Dakota counties entirely on an Indian reservation. (The others are Corson, Dewey, Todd, and Ziebach.) The county's per-capita income makes it the poorest county in the United States.
Note: Created before 1880; included with Pine Ridge Indian Reservation in 1890-1910; reported in 1920-90.