<P> In 1795, the number of stars and stripes was increased from 13 to 15 (to reflect the entry of Vermont and Kentucky as states of the Union). For a time the flag was not changed when subsequent states were admitted, probably because it was thought that this would cause too much clutter . It was the 15 - star, 15 - stripe flag that inspired Francis Scott Key to write "Defence of Fort M'Henry", later known as "The Star Spangled Banner", which is now the American national anthem . The flag is currently on display in the exhibition, "The Star - Spangled Banner: The Flag That Inspired the National Anthem" at the Smithsonian Institution National Museum of American History in a two - story display chamber that protects the flag while it is on view . </P> <P> On April 4, 1818, a plan was passed by Congress at the suggestion of U.S. Naval Captain Samuel C. Reid in which the flag was changed to have 20 stars, with a new star to be added when each new state was admitted, but the number of stripes would be reduced to 13 so as to honor the original colonies . The act specified that new flag designs should become official on the first July 4 (Independence Day) following admission of one or more new states . The most recent change, from 49 stars to 50, occurred in 1960 when the present design was chosen, after Hawaii gained statehood in August 1959 . Before that, the admission of Alaska in January 1959 prompted the debut of a short - lived 49 - star flag . </P> <P> Prior to the adoption of the 48 - star flag in 1912, there was no official arrangement of the stars in the canton, although the U.S. Army and U.S. Navy used standardized designs . Throughout the 19th century there was an abundance of different star patterns, rectangular and circular . </P> <P> On July 4, 2007, the 50 - star flag became the version of the flag in longest use, surpassing the 48 - star flag that was used from 1912 to 1959 . </P>

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