The original United States flag had thirteen stripes representing the thirteen colonies.
The Flag Resolution of June 14, 1777, described a flag with thirteen alternating red and white stripes and thirteen white stars on a blue field. The stars represented a new constellation of states, while the stripes continued the earlier thirteen-colony symbolism.
As new states entered the Union, both stars and stripes increased for a time. In 1818, Congress established a lasting arrangement: the flag would return to thirteen stripes for the original colonies, while a new star would be added for each new state.
The current flag therefore has fifty stars and thirteen stripes. The number of stars changes when states are admitted, but the number of stripes remains fixed at thirteen to preserve the connection with the founding colonies.