On 5 October 1947, President Harry Truman delivered the first televised speech from the White House. In this speech, Truman asked Americans to change their food consumption patterns — no meat Tuesdays; no eggs or poultry on Thursdays — to help Europeans, who were starving.
Truman’s speech launched the TV presidency; all of his subsequent White House speeches were televised, even though most Americans (only 14,000 sets) did not own a television set. A month later, the first Senate committee hearing was televised. Truman later became the first political candidate to buy a television ad, in the 1948 presidential contest. However, President Franklin Roosevelt was the first to appear on television, 30 April 1939.
On the web: How The White House Discovered Television