1. The Treaty of Fort Laramie, which established boundaries and promised peace between various Native American tribes and the United States government, was signed on June 5, 1868. The treaty was significant for South Dakota because it included the Great Sioux Reservation, which covered most of western South Dakota.

2. On June 5, 1889, South Dakota became the 40th state in the United States. The territory had been established in 1861, but it took nearly 30 years of population growth and political maneuvering before it was granted statehood.

3. The Black Hills War began on June 5, 1876, when a group of Lakota warriors, led by Crazy Horse, ambushed a detachment of US soldiers in the northern Black Hills. The conflict escalated over the next several months and culminated in the Battle of the Little Bighorn later that summer.

4. In 1915, the first Rapid City Air Fair was held on June 5. The event featured a mix of military and civilian aircraft, including a demonstration by aviation pioneer Glenn Curtiss. The air fair helped establish Rapid City as a hub for aviation in the early 20th century.

5. On June 5, 1983, President Ronald Reagan delivered a speech in front of Mount Rushmore to commemorate the 50th anniversary of the monument's completion. The speech was notable for its emphasis on American exceptionalism and its defense of capitalism, which were themes of Reagan's presidency.