I have written about the American Revolution on 4th July entry and learn part of the American anthem, Spangled Star Banner. Banner is a synonim of flag. The current symbols of the Stars and Stripes Flag are the thirteen stripes (7 red and 6 white), representing the former thirteen colonies and fifty stars (five points ones) for each one of the American states, with the exception of Puerto Rico that has not the same rights as the others.
The first American flag has only thirteen stars in a blue blackground representing a new constellation. It was called the Union Flag.
The first Flag Day observance was on June 14, 1877, commemorating the 100th anniversary of the flag.