The first television shows were experimental, sporadic broadcasts viewable only within a very short range from the broadcast tower starting in the 1930s. Televised events such as the 1936 Summer Olympics in Germany, the 1937 coronation of King George VI in the UK, and David Sarnoff's famous introduction at the 1939 New York World's Fair in the US spurred a growth in the medium, but World War II put a halt to development until after the war. The 1947 World Series inspired many Americans to buy their first television set and then in 1948, the popular radio show Texaco Star Theater made the move and became the first weekly televised variety show, earning host Milton Berle the name "Mr Television" and demonstrating that the medium was a stable, modern form of entertainment which could attract advertisers. The first national live television broadcast in the US took place on September 4, 1951 when President Harry Truman's speech at the Japanese Peace Treaty Conference in San Francisco was transmitted over AT&T's transcontinental cable and microwave radio relay system to broadcast stations in local markets.
The first national color broadcast (the 1954 Tournament of Roses Parade) in the US occurred on January 1, 1954. During the following ten years most network broadcasts, and nearly all local programming, continued to be in black-and-white. A color transition was announced for the fall of 1965, during which over half of all network prime-time programming would be broadcast in color. The first all-color prime-time season came just one year later. In 1972, the last holdout among daytime network shows converted to color, resulting in the first completely all-color network season.