1. The Battle of Whitemarsh took place on December 23, 1777, in Montgomery County, Pennsylvania. The Continental Army, led by General George Washington, fought against General William Howe's British troops. Although the battle ended in a stalemate, it was a morale boost for the Continental Army, who were still reeling from losses suffered earlier that year.

2. On December 23, 1828, the Pennsylvania State Canal Commission was established. This was a crucial step in the development of Pennsylvania's canal system, which was an important mode of transportation for goods and people in the 19th century.

3. The Pennsylvania Railroad was incorporated on December 23, 1846, in Philadelphia. The railroad was a major player in the development of transportation and commerce in Pennsylvania and beyond, and helped connect the state to the rest of the country.

4. The first National Christmas Tree was lit on December 23, 1923, in Washington, D.C. The tree was a gift from Pennsylvania, and was decorated with 2,500 electric bulbs. Today, the National Christmas Tree Lighting Ceremony is a popular tradition, and the tree is decorated with thousands of LED lights and ornaments from each of the 50 states.

5. On December 23, 2005, 12 miners were trapped in the Quecreek Mine in Somerset County, Pennsylvania, after a water-filled abandoned mine breached into their working area. A dramatic rescue effort ensued, with drilling teams working around the clock to reach the trapped miners. All 12 were rescued after three days underground, and the incident highlighted the dangers of mining and the importance of safety measures.