1. On April 3, 1869, the first stagecoach arrived in Deadwood, South Dakota, marking the beginning of a major transportation route for the city during the Black Hills Gold Rush.

2. In 1921, the notorious outlaw and South Dakota native Tom Horn was executed in Cheyenne, Wyoming, for the murder of a 14-year-old boy. Horn had a long criminal career, including stints as a cowboy, Indian scout, and hired assassin.

3. April 3, 1942, was the date that a United States Army Air Forces bomber crashed into Bear Butte, a prominent geological formation in western South Dakota. All ten crew members were killed in the crash, which occurred during a training exercise.

4. In 1974, South Dakota became the first state in the country to pass a law requiring all motorcyclists to wear helmets. The law was later repealed in 1977, but reinstated in 1989.

5. On April 3, 2006, the state of South Dakota enacted a law banning nearly all abortions within the state, with exceptions only in cases where the life of the mother was at risk. The law was ultimately struck down by the United States Supreme Court in 2020.