1. In 1863, the Battle of Honey Springs took place. It was one of the largest Civil War battles in what is now Oklahoma, but many of the troops involved were from Pennsylvania.

2. In 1920, the first commercial radio station in the United States, KDKA in Pittsburgh, began broadcasting. This event marked the beginning of a new era in mass communication.

3. In 1955, Disneyland opened its doors in Anaheim, California. While this isn't directly related to Pennsylvania, it's worth noting that many Pennsylvanians have visited the theme park over the years.

4. In 1967, Eastern State Penitentiary in Philadelphia closed its doors for good. The prison was once one of the most famous in the world and had housed some of the most notorious criminals in history.

5. In 1975, the U.S. Postal Service introduced ZIP codes. This change was designed to make sorting and delivering mail more efficient and accurate. It's worth noting that ZIP codes were first introduced in Pennsylvania in 1963, as part of a pilot program.