The 13 stripes on the United States flag represent the original 13 colonies, a symbol especially relevant during America250.
The stripes alternate red and white, with seven red stripes and six white stripes. They recall the colonies that declared independence from Great Britain in 1776 and became the foundation of the United States. The stars, by contrast, represent the states in the Union and therefore change as the number of states changes.
The first national flag resolution was adopted by the Continental Congress on June 14, 1777. It established a design with 13 alternating stripes and 13 stars. Over time, additional stars were added for new states, but the number of stripes was fixed at 13 in 1818. This is why the modern flag has 50 stars but still retains 13 stripes.