According to the Flag Resolution of 1777, thirteen stripes represent the original American colonies on the United States flag.
On June 14, 1777, the Continental Congress resolved that the flag should have thirteen alternating red and white stripes. The same resolution called for thirteen white stars on a blue field, representing a new constellation. The stripes therefore memorialized the colonies that declared independence and formed the original United States.
The number of stars later changed as new states joined the Union, but the number of stripes did not remain tied to the total number of states. In 1795, Congress temporarily increased the flag to fifteen stripes after Vermont and Kentucky became states. The 1818 flag law restored the number to thirteen and reserved new additions for stars.
The current flag has fifty stars and thirteen stripes. The fifty stars represent the current states, while the thirteen stripes preserve the founding-era symbolism. Flag Day is observed annually on June 14, the date associated with the 1777 resolution.