1. Earth Day was first celebrated on April 22, 1970, in Pennsylvania: The concept of Earth Day was first proposed by the late Senator Gaylord Nelson in 1969. The first Earth Day celebration took place on April 22, 1970, in several cities across the United States, and one of the largest events was held on Philadelphia's Belmont Plateau.

2. The Pennsylvania Turnpike opened on April 22, 1940: The Pennsylvania Turnpike, which is one of the first limited-access highways in the United States, opened to traffic on April 22, 1940. The turnpike, which spans 360 miles from Ohio to Philadelphia, was constructed over several years during the Great Depression.

3. The Gettysburg Address monument was dedicated on April 22, 1909: The Gettysburg Address monument, which is located in the Soldiers' National Cemetery in Gettysburg, was dedicated on April 22, 1909, to commemorate the 45th anniversary of the Battle of Gettysburg. The monument was designed by architect Paul J. Pelz and sculptor Henry Kirke Bush-Brown.

4. The first American flag was made in Pennsylvania on April 22, 1777: It is believed that the first American flag was made by Betsy Ross in her home in Philadelphia on April 22, 1777. Ross, a seamstress and upholsterer, was commissioned by George Washington to create a flag for the new nation.

5. The Pennsylvania Capitol Building was dedicated on April 22, 1906: The Pennsylvania Capitol Building, which is located in Harrisburg, was dedicated on April 22, 1906. The building, which was designed by architect Joseph Huston, features a grand staircase, a dome that is over 300 feet tall, and numerous pieces of artwork and decorative features.