It aired on radio from January 25, 1937 to June 29, 1956 and debuted on CBS Television on June 30, 1952. The final story airs on CBS on September 18, 2009. It is also the longest running broadcast program of any kind (72 years), across both radio and then television mediums, in history, being first broadcast five days after President Franklin D Roosevelt's second inauguration.
http://en.wikipedia.org/wiki/Guiding_Light
Wowzers.