George M. Cohan himself always proudly claimed--in interviews, in song, and in his autobiography, Twenty Years onBroadway--that he was "a real live nephew of my Uncle Sam's, born on the Fourth of July."
In his biography, George M. Cohan: Prince of the American Theater, Ward Morehouse argued that Cohan was likely born on July 3rd, not July 4th. However in his biography, George M. Cohan: The Man Who Owned Broadway, John McCabe argued that Cohan was indeed born on the Fourth.
Whatever the reality, we'd like to say, "Happy birthday, George!"