Warren G. Harding became the first U.S. President to broadcast a message over the radio as his voice was first heard on radio during a speech at the dedication of the Lincoln Memorial.
He went on to do it again on June 14, 1922 while speaking at the dedication of a memorial to Francis Scott Key in Baltimore and again on December 8, 1922 when his Annual Address to Congress (now known as the State of the Union) was broadcasted by Naval radio stations NOF and NAA.