1. On August 11, 1876, the Battle of Slim Buttes occurred in present-day Harding County. It was one of several battles between the United States Army and the Lakota Sioux during the Black Hills War. The battle resulted in a victory for the Sioux.

2. August 11, 1945, was the day that the first atomic bomb was dropped on the Japanese city of Nagasaki, effectively ending World War II. Many South Dakotans had served in the war effort, including members of the South Dakota National Guard.

3. In 1962, the state of South Dakota celebrated its 75th anniversary on August 11. The year-long celebration included parades, fairs, and other events throughout the state.

4. On August 11, 1978, a major tornado outbreak occurred in eastern South Dakota. Several tornadoes touched down, causing significant damage and killing one person.

5. August 11, 2017, marked the opening of the new Avera on Louise Health Campus in Sioux Falls. The state-of-the-art facility offers a range of health services, including emergency care, surgery, and cancer treatment.