1. The First Railroad to Enter South Dakota Was Completed on May 24, 1872
On May 24, 1872, the first railroad to enter South Dakota was completed when the Chicago and North Western Railway Company laid track into the town of Yankton. This was a major milestone for the state as it provided a more efficient way to transport goods and people in and out of the area.

2. Mount Rushmore Was Declared a National Monument on May 24, 1925
One of the most iconic landmarks in South Dakota, Mount Rushmore, was declared a National Monument on May 24, 1925. The monument was designed by sculptor Gutzon Borglum and features the faces of four U.S presidents: George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln.

3. The First US Airmail Service Started on May 24, 1918
On May 24, 1918, the first US airmail service started in South Dakota from the town of Deadwood to the city of Cheyenne, Wyoming. The service was initially designed to speed up the delivery of mail across the country and has since become a staple of the modern-day postal service.

4. The Last Native American Wounded in the 1890 Wounded Knee Massacre Died on May 24, 1973
On May 24, 1973, the last Native American wounded in the 1890 Wounded Knee Massacre, Frank Fools Crow, passed away at the age of 99. The massacre was a tragic event in South Dakota's history, where US troops killed over 200 Native Americans, including women and children.

5. The Battle of Vermillion Took Place on May 24, 1865
The Battle of Vermillion was a significant military engagement that took place on May 24, 1865, between US Army troops and the Sioux tribe in South Dakota. The battle was part of a larger conflict between the US government and various Native American tribes in the region that lasted for several decades. Although the US military was victorious in the Battle of Vermillion, the conflict ultimately resulted in the forced relocation of many Native American tribes and the loss of their ancestral homelands.