1. May Day celebrations, including the crowning of a May Queen, were popular in early Pennsylvania. Many German immigrants brought with them the tradition of Maifest, where villages would celebrate the arrival of spring with dancing and games.

2. The Haymarket affair in Chicago on May 1, 1886, had a ripple effect throughout Pennsylvania. The event led to a nationwide movement for an eight-hour workday, and in Pennsylvania, labor unions started organizing and demanding better work conditions and pay.

3. On May 1, 1898, Commodore George Dewey led the American fleet to victory over the Spanish navy in the Battle of Manila Bay. This event paved the way for U.S. control over the Philippines, Guam, and Puerto Rico, which had a significant impact on Pennsylvania's economy and military might.

4. In 1927, construction began on the Holland Tunnel, which connected New Jersey to Manhattan. The tunnel opened up new transportation routes for Pennsylvania, as it made it easier for residents to travel from Pennsylvania to New York.

5. May 1, 1961, was the day that Led Zeppelin played their first concert under that name. The iconic rock band went on to become one of the most influential groups of all time, and their music has had a lasting impact on Pennsylvania's music scene.