Congress adopted the Flag Resolution establishing 13 stripes and 13 stars on June 14, 1777.
The resolution stated that the flag of the thirteen United States would have thirteen alternating red and white stripes and thirteen white stars on a blue field. It did not specify a precise star arrangement, flag size, or detailed color standards, so early flags varied in appearance.
June 14 is now observed as Flag Day in the United States. The resolution came during the Revolutionary War, less than a year after the Declaration of Independence, when the new country needed a recognizable national symbol for ships, forts, and military forces.
The flag later changed as states entered the Union. In 1795, both stars and stripes increased to 15 for Vermont and Kentucky. In 1818, Congress restored the stripes to 13 and established the practice of adding a star for each new state.