1. On September 20, 1630, the first General Court of Massachusetts, made up of representatives from several towns, was held in Boston. This marked the beginning of self-government for the colony.

2. In 1777, the Battle of Saratoga began, in which American forces led by General Horatio Gates defeated British troops led by General John Burgoyne. This was a major turning point in the Revolutionary War and helped secure France's support for the American cause.

3. On September 20, 1830, the Tom Thumb, the first locomotive built in America for commercial use, had its inaugural run in Hagerstown, Maryland. It was later used on the Baltimore and Ohio Railroad.

4. The opening ceremony for the Boston Common, America's oldest public park, was held on September 20, 1830. The park has served as a gathering place for Bostonians for over 300 years and is still a popular destination for locals and visitors alike.

5. In 1999, a teenage boy named Jaylen Fryberg opened fire in the cafeteria of Marysville Pilchuck High School in Marysville, Washington, killing four students and injuring several others before taking his own life. Fryberg was a member of the Tulalip Tribes and the shooting prompted a renewed discussion about gun control and the mental health of young people.