1. Nebraska became a state: May 20, 1867 marks the day when Nebraska officially became the 37th state of the United States, after being established as a territory in 1854.

2. The opening of Boys Town: In 1917, on May 20th, the renown Boys Town was established by Father Edward Flanagan in Omaha, Nebraska. Boys Town remains a symbol of hope and support for at-risk children and their families.

3. The first successful parachute jump: In 1919, on May 20th, Charles Lindbergh, a barnstorming pilot, made his first successful parachute jump in the town of Lincoln, Nebraska. He would go on to become a pioneer in aviation history.

4. The landmark U.S. Supreme Court Case: In 1968, May 20th was the day when the U.S. Supreme Court handed down the landmark decision in the case of United States v. Jackson which upheld the right of indigent defendants to have access to the courts and assistance of appointed defense counsel in criminal proceedings.

5. The tragic school shooting: On May 20, 1999, tragedy struck when two students opened fire at Columbine High School in Littleton, Colorado which resulted in the deaths of 12 students and one teacher. The event had a profound impact on the nation, including Nebraska, which implemented stricter gun control measures in the years following the shooting.