Said to be the second most sung song in the English language after "Happy Birthday." The melody's origins are from early 18th century France, the varying English words having evolved throughout the 19th century in Britain ("...and so say all of us...") and America ("...which nobody can deny..."). Genuinely old and used enough to be considered a "folk song."
Words & music by one-man American entertainment phenomenon George M. Cohan(1878-1942). From his musical "Little Johnny Jones," 1904.