1. On June 25, 1876, the Battle of the Little Bighorn began in Montana, but several members of the Sioux Tribe who participated in the battle were from South Dakota. The battle took place between the U.S. Army's 7th Cavalry Regiment and a combined force of Lakota, Northern Cheyenne, and Arapaho tribes.

2. On June 25, 1908, the first automobile racing event in South Dakota took place in Huron. The race was organized by local promoters and featured several cars competing in a 50-mile race around a track.

3. On June 25, 1936, the state's first official highway patrol was established. The South Dakota Highway Patrol was created to help enforce traffic laws and promote safer driving practices throughout the state.

4. On June 25, 1944, the International Harvester Company opened a new manufacturing facility in Sioux Falls. The plant produced a variety of farm equipment and tractors, which helped support the state's agricultural economy.

5. On June 25, 1972, the Black Hills Flood occurred. Heavy rainfall caused several dams to fail, including the Canyon Lake Dam in Rapid City. The resulting flood killed 238 people and caused widespread damage throughout the area. The disaster is still considered one of the deadliest floods in U.S. history.