1. On December 9, 1882, the Missouri River froze solid near Yankton, South Dakota, causing a massive ice dam that blocked the river and caused flooding downstream. The flooding caused extensive damage to homes, farms, and businesses in Missouri, Iowa, and Nebraska.

2. On December 9, 1905, South Dakota became the first state in the nation to allow women to vote in state elections, nine years before the 19th Amendment to the U.S. Constitution granted women the right to vote nationwide.

3. On December 9, 1929, the Black Hills ski area, now known as Terry Peak, opened for business. Located near Lead, South Dakota, Terry Peak is one of the largest ski resorts in the region and attracts thousands of visitors every winter.

4. On December 9, 1946, the Rapid City Journal reported on a sighting of a flying saucer over the Black Hills. The sighting sparked a wave of UFO sightings in the region and helped popularize the belief in extraterrestrial life.

5. On December 9, 1968, South Dakota Governor Frank Farrar declared a state of emergency in response to a major blizzard that hit the state. The blizzard, which lasted for three days and dropped up to three feet of snow in some areas, resulted in 20 deaths and caused millions of dollars in damage.