When the American Revolution broke out in 1775, the colonists weren’t
fighting united under a single flag. Instead, most regiments participating
in the war for independence against the British fought under their own
flags. In June of 1775, the Second Continental Congress met in
Philadelphia to create the Continental Army—a unified colonial fighting
force—with the hopes of more organized battle against its colonial
oppressors. This led to the creation of what was, essentially, the first
“American” flag, the Continental Colors. For some, this flag, which
was comprised of 13 red and white alternating stripes and a Union
Jack in the corner, was too similar to that of the British. George
 Washington soon realized that flying a flag that was even remotely
close to the British flag was not a great confidence-builder for the
revolutionary effort, so he turned his efforts towards creating a new
symbol of freedom for the soon-to-be fledgling nation.

On June 14, 1777, the Second Continental Congress passed a resolution
stating that “the flag of the United States be 13 stripes, alternate red and
white,” and that “the union be 13 stars, white in a blue field, representing
a new constellation.” In 1916, President Woodrow Wilson marked the
anniversary of that decree by officially establishing June 14 as Flag Day.