1. On April 7, 1874, a battle between Sioux warriors and the United States Army took place near Beaver Creek in present-day Harding County. The battle, known as the Battle of the Little Missouri, resulted in the death of several soldiers and Sioux warriors.

2. In 1880, construction of the first railroad line into Rapid City began. The line was completed in 1886, opening up new economic opportunities for the city and the surrounding area.

3. On April 7, 1927, the state flag of South Dakota was officially adopted. The flag features the state seal surrounded by the words "South Dakota" and "The Mount Rushmore State."

4. In 1936, the first Gutzon Borglum Memorial Society meeting was held in Rapid City. The society was formed to honor the sculptor of Mount Rushmore and promote his legacy.

5. On April 7, 1972, a blizzard struck South Dakota, dropping over two feet of snow in some areas and causing significant damage and disruptions. The blizzard, known as the Easter Blizzard, caused widespread power outages and transportation closures.