Final answer:
In the 1920s, radio programs started to be funded by advertising, with the creation of networks such as NBC and CBS. This led to a diverse mix of content including news, entertainment, and educational programs reaching a wide audience and marking the beginning of the 'Golden Age' of radio.
Step-by-step explanation:
In the 1920s, radio programs began to be financed through a groundbreaking method known as advertising. New networks such as the National Broadcasting Company (NBC), the Columbia Broadcasting System (CBS), and the American Broadcasting Company (ABC) introduced the advertiser-supported programming format that became the cornerstone of both radio and television.
This innovative approach to funding allowed for an array of content, including sponsored news programs, comedy, drama, talk shows, religious and educational programs, and by the late 1930s, even game shows and quiz shows. The advertising revenue model helped create the “Golden Age” of radio, diversifying and expanding content that reached almost 83 percent of American households by 1940.