American Top 40 (abbreviated to AT40) is an internationally syndicated, independent song countdown radio program created by Casey Kasem, Don Bustany, Tom Rounds, and Ron Jacobs. The program is currently hosted by Ryan Seacrest and presented as an adjunct to his weekday radio program, On Air with Ryan Seacrest.
On July 4, 1970, the countdown started. Originally hosted by Casey Kasem, American Top 40 played “the best-selling and most-played songs from the Atlantic to the Pacific, from Canada to Mexico,” as he stated on the first program broadcast 50 years ago as of tomorrow.
The show began as a three-hour program written and directed by Bustany, counting down the top 40 songs on Billboard’s Hot 100 Singles chart. The show quickly gained popularity once it was commissioned, and expanded to a four-hour program on October 7, 1978, to reflect the increasing average length of singles on Billboard’s Hot 100 chart.
By the early 1980s, the show was heard on more than 500 stations across America and on the Armed Forces Radio Network around the world.
Currently, American Top 40 with Seacrest airs in two formats, with one distributed to Contemporary Hit Radio (Top 40) stations and the other to Hot Adult Contemporary stations. However, there is no distinction made between the two shows on air. There are also two classic editions of the original American Top 40 distributed every weekend, featuring past Kasem-hosted shows from the 1970s and 1980s.
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