The 1777 Flag Resolution required 13 stars on the U.S. flag.
On June 14, 1777, the Continental Congress resolved that the flag of the thirteen United States should have thirteen alternating red and white stripes and thirteen white stars in a blue field. The stars represented the thirteen states as a new constellation.
The resolution did not specify how the stars should be arranged, how many points they should have, or whether they should form a circle or rows. As a result, early flags varied in appearance even though they followed the same basic numerical requirement.
The number of stars changed as new states joined the Union. Congress temporarily added stars and stripes for Vermont and Kentucky in 1795, but the Flag Act of 1818 returned the stripes to 13 and established that future additions would be stars only. The current flag has 50 stars.