Flag Day became an official holiday in 1949 when President Harry S. Truman signed legislation establishing June 14 as Flag Day in the United States. President Woodrow Wilson signed an executive order in 1916 commemorating Flag Day, but Congress did not act until 1949.
Flag Day is celebrated on June 14 because that date in 1777 is when the Continental Congress approved the first design of the American flag. As of 2014, there have been 27 different designs for the flag because a star is added every time a state joins the union. Flagmakers' preferences determined the placement of stars on the blue field until 1912 when President William Howard Taft standardized the stars into rows.