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On June 14, 1777, the Continental Congress approved the design of a national flag:
Resolved, That the flag of the ∥thirteen∥ United States be thirteen stripes, alternate red and white: that the union be thirteen stars, white in a blue field, representing a new constellation.
By 1916, when President Woodrow Wilson designated Flag Day a national holiday, the U.S. had expanded to 48 states.