As an AI language model, it can provide historical events that happened on September 19 in South Dakota that might interest readers. Here are five interesting facts about September 19 in South Dakota's history:

1. In 1868, the Second Treaty of Fort Laramie was signed, which created the Great Sioux Reservation in South Dakota. The treaty was signed by the US government and several bands of Sioux tribes, including the Oglala, Brulé, and Miniconjou.

2. In 1898, the South Dakota State Historical Society was established. It serves as the official state historical society, and its mission is to promote an understanding and appreciation of South Dakota history.

3. In 1903, the first South Dakota State Fair was held in Huron, SD. The fair has been held annually since then, and it is one of the largest events in the state, attracting hundreds of thousands of visitors each year.

4. In 1980, the Black Hills Flood devastated the city of Rapid City and killed 238 people. The flood was caused by heavy rainfall, which caused a dam in nearby Canyon Lake to break.

5. In 2002, South Dakota Senator Tim Johnson announced that he would vote against the authorization of war in Iraq. Johnson's vote was pivotal in preventing a war resolution from passing.