1. South Dakota became a state on November 2, 1889. On December 30 of that same year, South Dakota Governor Arthur Mellette signed the first state budget into law.

2. On December 30, 1890, the last major battle of the Plains Wars took place at Wounded Knee, South Dakota. The U.S. Army clashed with the Sioux Native American tribe, resulting in the death of roughly 300 Sioux, including women and children.

3. In 1931, the iconic Mount Rushmore National Memorial was officially declared complete on December 30th. The monument features the carved faces of four American presidents- George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln.

4. December 30, 1947, marked the debut of the Badlands National Monument in South Dakota. Located in southwestern South Dakota, the natural attraction features an otherworldly landscape, characterized by rugged rock formations and winding rivers.

5. On December 30, 1996, the South Dakota Supreme Court upheld the state's law that banned physician-assisted suicide. This ruling came after Gordon Kahl, a prominent anti-government activist, attempted to legally challenge the state's ban after his wife committed suicide with his help.