1. On March 31, 1832, the state of Pennsylvania passed the first legislation regulating child labor. The law prohibited children under the age of 12 from working in factories and limited the workday for children between the ages of 12 and 18 to 10 hours.

2. In 1917, on March 31, Pennsylvania became the first state to establish a state police force. The Pennsylvania State Police were created as a response to growing crime rates and to provide law enforcement in rural areas of the state.

3. On March 31, 1943, Pennsylvania-born artist Andrew Wyeth's painting "Christina's World" was exhibited for the first time in New York City. The iconic painting, which depicts a woman crawling through a field towards a farmhouse, became one of Wyeth's most famous works and is now in the collection of the Museum of Modern Art.

4. On this day in 1960, the first case of the H1N1 virus (commonly known as swine flu) was reported in a pig at a farm in Lancaster County, Pennsylvania. The virus would go on to affect humans worldwide in the late 2000s and early 2010s.

5. March 31, 1865, marked the end of the Battle of Five Forks during the American Civil War. The Union Army, led by General Philip Sheridan, defeated Confederate forces under General George Pickett and secured a vital supply line to Petersburg, Virginia. The battle was a turning point in the Civil War and helped lead to the fall of the Confederacy.