1. William Penn arrived in Philadelphia: On May 24, 1682, William Penn, the founder of Pennsylvania, arrived in the colony's capital city of Philadelphia. He was greeted by Native American representatives and began to establish a government and legal system based on Quaker principles.

2. First Philadelphia Mint opened: The first United States Mint in Philadelphia began operations on May 24, 1792. The mint produced coins for circulation until 1980, and today it is a popular tourist attraction.

3. Great Railroad Strike of 1877: On May 24, 1877, railroad workers across the country went on strike to protest low wages and poor working conditions. The strike began in Martinsburg, West Virginia, and soon spread to other states, including Pennsylvania. The National Guard was called in to break up protests and restore order.

4. Johnstown Flood: On May 31, 1889, a dam broke in Johnstown, Pennsylvania, causing a massive flood that killed over 2,200 people. However, on May 24, heavy rain and thunderstorms caused the river to rise, leading up to the disaster.

5. Pennsylvania Turnpike opened: The Pennsylvania Turnpike, the first long-distance highway in the United States, opened on October 1, 1940. However, on May 24 of the same year, portions of the turnpike in eastern Pennsylvania were opened to the public, marking a significant milestone in American transportation history.