The Continental Congress adopted the Flag Resolution on June 14, 1777.
The resolution specified that the flag of the thirteen United States should have thirteen alternating red and white stripes and thirteen white stars on a blue field. It did not prescribe the stars’ arrangement, exact dimensions, or many details associated with later flag specifications.
June 14 is now observed as Flag Day in the United States. The resolution was passed during the Revolutionary War, when the new country was developing symbols to distinguish its forces and ships from British authority. Earlier flags, including the Grand Union Flag, had already been used before the 1777 resolution.
The popular story that Betsy Ross designed the entire American flag is not established by surviving contemporary evidence. Early flag makers used several star arrangements, including circles and rows. The modern flag evolved over time as stars were added for new states; the current 50-star design dates from 1960.