1970, Casey Kasem introduced the radio
show American Top 40 (AT40). It was a syndicated
broadcast distributed to radio stations in the United States,
Canada, Australia, Philippines, China, India, Great Britain,
Malaysia and many other places around the globe. As the name
suggests the program had a countdown playing the fourty most
popular songs in the U.S. according to the Billboard's Hot 100
Singles Chart. The most important with Casey Kasem as a deejay
was his anecdotes about the artists and songs that were played.
Behind him he had an editorial with, in its peak, a total of
From its inception in 1970 the duration of the show was 3 hours.
In the late 1970’s the program was prolonged up to 4 hours
to reflect the longer playing time of the music of those days.
Billboard's Hot 100 was concidered the given industry standard
for specifying the most popular songs for AT40 through the first
years. In the second half of the seventies the hit music was
so changed, resulting in an increasing specialization in formats
on the radio stations. Dissatisfaction grew between the radio
stations when AT40 continued to reflect the many different styles
and formats on the hot 100 list. Later, this lead to the result
that the Hot 100 chart was replaced by the Billboard’s
Radio and Records list.