On June 14, 1777, the Continental Congress adopted the stars and stripes design for the flag of the United States. While the first national observance of Flag Day occurred on June 14, 1877, the centennial of the adoption of the flag, it was not an official national observance until years later. President Wilson in 1916, and President Coolidge again in 1927, issued proclamations asking for June 14th to be observed as National Flag Day. However, Congress did not approve the national observance until August 3, 1949, and President Truman signed it into law.
More information is available at: