The American flag didn’t always have 13 stripes.
In 1794 the country added a star and stripe each for its two newest states, Kentucky and Vermont. This 15-star and 15-stripe flag is what was flying over Mt. McHenry when the lyrics that would become the “Star Spangled Banner” were written during the war of 1812. There were actually 15 broad stripes and bright stars gleaming through the perilous fight that day.
As more states like Tennessee, Ohio and Indiana were ratified, in 1818 Congress voted to reduce the number of stripes on the flag to 13 — symbolic of the original colonies.
– Margaret Willard, The 100 Companies