1. Earth Day: April 22 is celebrated worldwide as Earth Day, a holiday dedicated to raising awareness and promoting actions for environmental protection. South Dakota commemorates this day by organizing community events and promoting sustainable practices.

2. Great Sioux War: On April 22, 1876, the Great Sioux War began with the Battle of Ash Hollow, where native tribes fought against General George Crook's troops. The conflict would continue for months and affect the region's history for years to come.

3. Homestake Mine Incident: On April 22, 1930, a fire broke out in the Homestake Mine, one of the world's largest gold mines located in Lead, South Dakota. The fire caused extensive damage and casualties, but the mine continued to operate for several decades until its closure in 2002.

4. Chief Red Cloud's Visit: In 1874, Chief Red Cloud of the Oglala Lakota tribe visited Pierre, South Dakota, to meet with officials and discuss territorial issues. His visit was instrumental in shaping the state's relationship with native tribes and their rights.

5. Black Hills Expedition: On April 22, 1875, a geological expedition led by Lieutenant Colonel George Custer explored the Black Hills region of South Dakota, which had been annexed by the United States in violation of native treaties. The expedition would lead to further territorial conflicts and eventually the Battle of Little Bighorn.