Ancient history

What does it mean if you have a 1909 penny with no mint mark?

A 1909 penny with no mint mark was minted at the Philadelphia Mint. The Philadelphia Mint is the oldest and largest mint in the United States. It is located in Philadelphia, Pennsylvania, and has been producing coins since 1792. The Philadelphia Mint does not put a mint mark on its coins, so all 1909 pennies minted in Philadelphia will not have a mint mark.