A nuclear disaster occurred at Three Mile Island in Pennsylvania, US.
A giant ball of fire was seen arching across the sky from Michigan to Pennsylvania.
The first newspaper from a vending machine was bought in Columbia, Pennsylvania.
Polio vaccines were given to the first group of children in the US at Arsenal Elementary School in Pittsburgh, Pennsylvania.
The Marianna Coal Mine in Pennsylvania exploded and killed 154 men.
One hundred and forty thousand miners went on strike in Pennsylvania.
Milton S. Hershey founded Hershey's Chocolate Company in Lancaster, Pennsylvania, US.
The first motion picture was shown to a theater audience at the Philadelphia Academy of Music.
American driller Edwin Laurentine Drake successfully drilled the first oil well in Pennsylvania, US.
The Women's College of Pennsylvania, US opened – making it the 2nd female medical school in America.
Harriet Tubman escaped from slavery.
The Portage Railroad Line in Pennsylvania built the first railroad tunnel in the US.
Blacksmith, Patrick Lyon stole $162,821 in cash and gold from a vault at the Bank of Pennsylvania.
America's second president John Adams was inaugurated in Philadelphia, Pennsylvania.
Pennsylvania became the second state to ratify the US constitution.
The first US commercial bank, The Bank of North America, opened in Philadelphia.
During the American Revolution, Lancaster in Pennsylvania became the capital of the United States for just one day.
The American Declaration of Independence was publicly released in the Pennsylvania Evening Post.
The Grand Union Flag flew for the first time with the commissioning of the USS Alfred.
The United States Marine Corps was founded when two battalions of Continental Marines came together in Philadelphia, Pennsylvania.
The first Continental Congress meeting was held in Philadelphia, US.
The first music store in America was opened in Philadelphia by Michael Hillegas.
The famous Liberty Bell arrived in Philadelphia, US.
Thirteen Mennonite families arrived in Philadelphia from Germany.
Englishman William Penn founded Philadelphia, Pennsylvania.
