1. In 1872, the first Arbor Day celebration in Pennsylvania was observed in Erie County. This day is meant to encourage people to plant and care for trees in their communities. Today, Arbor Day is celebrated across the United States on the last Friday in April.

2. In 1954, the Susquehanna River Basin Compact was signed into law. This agreement between Pennsylvania, Maryland, and New York created a regional organization to manage water resources in the Susquehanna River Basin. Today, the Susquehanna River Basin Commission continues to oversee water management throughout the region.

3. In 1983, the Pennsylvanian state bird, the Ruffed Grouse, was designated the official bird of Pennsylvania. This decision was based on the bird's popularity among hunters and outdoors enthusiasts, as well as its widespread distribution throughout the state.

4. In 2014, Pennsylvania Governor Tom Corbett signed a law legalizing medical marijuana in the state. This made Pennsylvania the 24th state in the country to allow for the use of medical cannabis. Today, marijuana continues to be a controversial issue in the state, with some advocating for full legalization while others remain opposed.

5. In 2015, the Pennsylvania Supreme Court struck down the state's congressional district map, ruling that it had been unconstitutionally gerrymandered to favor the Republican Party. This decision led to the creation of a new, more even district map ahead of the 2018 election. The case remains one of the most significant examples of redistricting reform in recent US history.