1889    President Grover Cleveland signs a bill admitting North Dakota, South Dakota, Montana and Washington as U.S. states.

1889    North and South Dakota are admitted as the 39th and 40th U.S. states.

1975    Two FBI agents and a member of the American Indian Movement are killed in a shootout on the Pine Ridge Indian Reservation in South Dakota; Leonard Peltier is later convicted of the murders in a controversial trial.

2006    South Dakota Governor Mike Rounds signs legislation banning most abortions in the state.