1. On June 20, 1782, a group of Pennsylvania militiamen led by Captain David Williamson killed 96 peaceful Delaware Indians in what came to be known as the Gnadenhutten massacre. The incident provoked outrage and condemnation from both Native American and white communities.
2. On June 20, 1813, the Battle of McGraw's Ford took place near Hanover, Pennsylvania, during the War of 1812. After a brief skirmish, American forces under Brigadier General Alexander Smyth withdrew, leaving the British in control of the area.
3. On June 20, 1863, Confederate General Richard Ewell's troops captured the town of York, Pennsylvania, during the Gettysburg Campaign. Ewell declined to lay waste to the city, instead demanding a ransom of $100,000 in exchange for sparing it from destruction.
4. On June 20, 1917, the state of Pennsylvania implemented new legislation regulating the production and sale of milk. Known as the Milk Control Law, it established standardized testing procedures, quality standards, and pricing agreements for the dairy industry.
5. On June 20, 1990, the Supreme Court of Pennsylvania issued a ruling in Commonwealth v. Hunt, effectively overturning decades of discriminatory hiring practices in the state's civil service. The decision mandated that all qualified candidates for public employment be considered on an equal basis, regardless of race, gender, or other factors.