1. In 1777, the Battle of Paoli took place in present-day Malvern, Pennsylvania. Also known as the "Paoli Massacre," British troops surprised and attacked a Continental Army camp, killing over 50 soldiers.

2. Pennsylvania's first constitution was adopted on September 28, 1776, but before that, on September 20, 1776, a preliminary version was signed by members of the state's revolutionary committee in Lancaster.

3. The Appalachian Trail, a 2,200-mile hiking trail from Georgia to Maine, passes through Pennsylvania. On September 20, 1927, the trail was officially completed and open for hiking.

4. The Philadelphia Phillies won their first National League pennant on September 20, 1915, defeating the Boston Braves 5-0. The team went on to win the World Series against the Chicago White Sox.

5. On September 20, 1994, the United States Postal Service released a stamp honoring Betsy Ross, the Philadelphia seamstress credited with sewing the first American flag. The stamp was part of a series honoring women who had made significant contributions to American history.