On April 4, 1818, Congress passed a law that fixed the number of stripes on the U.S. flag at thirteen and set one star for each state. Before this act, states had been added without a clear rule for changing the flag. The law honored the original thirteen colonies by keeping thirteen stripes while allowing stars to expand with the Union. It required that new stars be added on the Fourth of July following the admission of a new state. The 1818 act created the basic pattern used for the flag ever since. Each change in the number of stars reflects a new chapter in U.S. expansion and statehood.
