1. Birth of Francis Case: June 12 marks the birth anniversary of South Dakota's celebrated Congressman Francis Case. He served in the House of Representatives for six terms starting from 1937, and then in the Senate from 1951 until his death in 1962. Case led many successful conservation efforts, including funding for the Missouri River Basin project.

2. Battle of the Rosebud: On June 17, 1876, one of the most significant battles of the Sioux Wars took place near the Rosebud River. Led by Crazy Horse and Chief Gall, the Lakota Sioux defeated General George Crook's forces, altering the course of the Sioux Wars and leading to the Battle of Little Bighorn just nine days later.

3. Pine Ridge Indian Reservation Established: On June 25, 1868, the Pine Ridge Indian Reservation was established by the United States government as a home for the Oglala Sioux tribe. The reservation covers over 1.7 million acres in southwestern South Dakota.

4. The Black Hills Expedition: On June 11, 1874, General George Custer led the Black Hills Expedition into the heart of the Black Hills region, where gold had been discovered. The expedition was met with opposition from the Sioux, who claimed ownership of the sacred land. The ensuing conflict led to the famous Battle of Little Bighorn two years later.

5. First Transcontinental Airmail Flight: On June 12, 1920, the first transcontinental airmail flight took off from New York and arrived in San Francisco 33 hours later. South Dakota played a crucial role in the airmail service, with several waypoints along the route, including Rapid City, Pierre, and Rawlins.