1. In 1889, South Dakota became the 40th state to join the Union. After years of territorial status and several failed attempts to gain statehood, South Dakota finally entered the United States as a state on October 9th of that year.

2. In 1952, the Black Hills Flood devastated the cities of Rapid City and the surrounding area in South Dakota. The flood was caused by heavy rains that lasted several days, and it claimed over 200 lives and caused millions of dollars in damages.

3. On October 9, 1942, the US Army announced the establishment of the Pine Ridge Indian Reservation. The reservation is home to the Oglala Sioux Tribe and covers over 2 million acres in southwestern South Dakota.

4. The Mount Rushmore National Memorial was dedicated on October 9, 1927. The sculpture features the faces of four US presidents - George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln - carved into the granite mountainside in the Black Hills.

5. In 1967, the South Dakota State Capitol building in Pierre was declared a National Historic Landmark. The neoclassical structure, which was completed in 1910, features a 165-foot dome and houses the offices of the governor and other state officials.