The national flag of the United States has thirteen horizontal stripes.
The stripes alternate red and white and represent the thirteen colonies that declared independence from Great Britain. The flag also has a blue canton containing stars that represent the states in the Union.
The Continental Congress adopted the first official national flag design on June 14, 1777. That resolution specified thirteen stripes and thirteen white stars, creating the design tradition commemorated by Flag Day.
The stripes stayed at thirteen even as the country admitted additional states. The stars changed over time, rising from thirteen to fifty. This distinction is a common source of confusion: the stripes refer to the original colonies, while the stars refer to the current states.