The Guiding Light was broadcast on NBC, then CBS radio from 1937-1956 and on CBS TV from 1952-2009.

The original NBC radio series (broadcast in 15-minute episodes) was based on the personal experiences of writers Emmons Carlson and Irna Phillips who found spiritual comfort in the radio sermons of Chicago preacher Preston Bradley, founder of the People’s Church. The series was transferred to CBS Radio in 1947.

Over the years, Guiding Light had many different cast members and plot sequences and different writers that developed complex story lines.

Airing for 72 years on radio and television, Guiding Light was America’s longest running soap opera. 

Source: Wikipedia