The flag of the Commonwealth of Pennsylvania consists of a blue field on which the state coat of arms is embroidered. Originally authorized by the state in 1799, the current design was enacted by law in 1907.
The state coat of arms is surrounded by draft horses on both sides, and a bald eagle, which represents Pennsylvania's loyalty to the United States, above. The state coat of arms includes a ship under full sail, a plow, and three sheaves of wheat indicating the significance of commerce, labor, perseverance and agriculture to the state. Surrounding the coat of arms is a stalk of Indian corn on the left and an olive branch on the right. These represent the state's recognition of its past and its hope for the future. The scroll below the coat of arms reads: "Virtue, Liberty and Independence," which is the state's motto.
Pennsylvania received the nickname "The Keystone State" in reference to its importance in early American history. Many documents, like the United States Declaration of Independence, were signed in the state. The state was also an economical "keystone", concentrating both industry, like North colonies, and agriculture, like South colonies. In some designs, it's substituted by keys.
William Penn was the founder of Province of Pennsylvania, that became the current Commonwealth of Pennsylvania. During his government, the city of Philadelphia was planned and developed. Moreover, he was also an early champion of democracy and religious freedom.
In his honor, Pennsylvania received the "The Quaker State" nickname, in reference to Penn's belonging in the quaker moviment.
Penn family's coat of arms can be blazoned as "argent, on a fess sable three plates".