Adopted: July 4, 1960
The design of the US flag was the result of a resolution adopted by the Second Continental Congress on June 14, 1777 that read:
Resolved: that the flag of the United States be thirteen stripes, alternate red and white; that the union be thirteen stars, white in a blue field, representing a new constellation.
There was no law (and still is none) concerning the arrangement of the stars. The current arrangement is according to executive order.
In 1795 the number of stars and stripes were increased to 15 each, reflecting the two new states (Vermont and Kentucky) that were admitted to the union. As new states were added, increasing the number of stripes would have been impractical, so Congress ordered that after July 4, 1818 the number of stripes would be set permanently at 13, representing the 13 original states, the number of stars would equal the number of states and that whenever a new state was added the flag would be altered on the next July 4. Because Hawaii became a state on August 21, 1959, the 50-star flag became official on July 4, 1960.