1. In 1921, the South Dakota legislature passed a law authorizing the establishment of a school for the deaf. This school still exists today and is located in Sioux Falls.

2. On April 28, 1943, Sioux Falls experienced a record-breaking snowstorm, with 20 inches of snowfall in one day. This remains the largest snowfall in the city's history.

3. In 1956, the South Dakota State College (now South Dakota State University) opened a new campus in Rapid City. This campus remains an important part of the university today.

4. On April 28, 1977, the Rapid City flood occurred, killing 238 people and causing $160 million in damages. This remains one of the deadliest natural disasters in South Dakota history.

5. In 1991, South Dakota governor George S. Mickelson and seven others died in a plane crash in Iowa. Mickelson was widely respected for his efforts to improve education and economic development in the state.