The program was hosted by Casey Kasem and co-created by Kasem Don Bustany, Kasem's childhood friend from Detroit, MI radio veteran Tom Rounds and 93/KHJ Program Director Ron Jacobs, who produced and directed the various production elements. In early 1982, Watermark was purchased by ABC Radio and AT40 became a program of the 'ABC Contemporary Radio Network'.

It was originally distributed by Watermark Inc., and was first presented in mono until February 24, 1973, when the first stereo vinyl copies were distributed. The first show featured the last time both Elvis Presley and The Beatles had songs simultaneously in the Top 10. The chart data broadcast actually included the top 40 songs from the week ending July 11, 1970. Billboard reported prior to the release of the show that it had been sold to stations in 10 radio markets. Casey Kasem at the beginning of the inaugural AT40 broadcastДЄmerican Top 40 fittingly began on the Independence Day weekend in 1970, on seven radio stations, the first being KDEO in El Cajon, California (now KECR), which broadcast the inaugural show the evening of July 3, 1970. In this hour at #32 in the countdown, a song that's been a hit 4 different times in 19 years! And we're just one tune away from the singer with the $10,000 gold hubcaps on his car! Now, on with the countdown! This is Casey Kasem in Hollywood, and in the next three hours, we'll count down the 40 most popular hits in the United States this week, hot off the record charts of Billboard magazine for the week ending July 11, 1970. Here we go with the Top 40 hits of the nation this week on American Top 40, the best-selling and most-played songs from the Atlantic to the Pacific, from Canada to Mexico.

10 Notable songs played on American Top 40.

7.4 Remixes and alternate versions of charted songs.

7.3 Lengthy songs and double-sided hits.

7 Censorship, offensive songs and affiliate standards.

3.2 Casey Kasem's American Top 40-the 70s and 80s.

1.3 1998вЂ“2004: American Top 40 returns second Casey Kasem era.

Through most of the 1980s, the countdown was compiled by Stu Jacobs. The current source for the AT40 charts are unpublished mainstream Top 40 and hot adult contemporary charts compiled by Mediabase.

The program subsequently switched to being based on Radio and Records airplay data upon its late 1990s return. In its early years, AT40 used the Billboard charts to compile the countdown, touting it as 'the only source'. There are also two classic editions of the original AT40 distributed every weekend, featuring past Kasem-hosted shows from the 1970s and 1980s. However, there is no distinction made between the two shows on air. Seacrest took over AT40 on January 10, 2004, following Kasem's retirement from the series.Д¬urrently, AT40 with Seacrest airs in two formats, with one distributed to Contemporary Hit Radio (Top 40) stations and the other to Hot Adult Contemporary stations. Kasem, who had spent nine years hosting his own countdown Casey's Top 40 for Westwood One, returned to hosting his creation on March 28, 1998. Three years later, Kasem teamed up with Premiere's predecessor AMFM Radio Networks to relaunch AT40. Shadoe Stevens took over the program on August 13, 1988, and hosted until January 28, 1995, when the original program came to an end. GEICO is the main sponsor for the show.Д¬o-creator Casey Kasem hosted the original AT40 from its inauguration on July 4, 1970, until August 6, 1988. It can also be heard on iHeartRadio, TuneIn and the official AT40 applications on mobile smartphones and tablets as well as on Xbox 360, Xbox One, PlayStation 4 consoles (via iHeartRadio's console app) and the Armed Forces Network. Nearly 500 radio stations in the United States, and several other territories worldwide air AT40, making it one of the most listened-to weekly radio programs in the world. (later a division of ABC Radio known as ABC Watermark, now Cumulus Media Networks), AT40 is now distributed by Premiere Networks (a division of iHeartMedia). Originally a production of Watermark Inc. The program is currently hosted by Ryan Seacrest and presented as an adjunct to his weekday radio program, On Air with Ryan Seacrest. HOT AC: KMYI (San Diego CA) KDMX (Dallas TX)Д¬asey Kasem, Don Bustany, Tom Rounds and Ron JacobsД®aston Allyn & Jennifer Sawalha (Present)ДЄmerican Top 40 (commonly abbreviated to AT40) is an internationally syndicated, independent song countdown radio program created by Casey Kasem, Don Bustany, Tom Rounds and Ron Jacobs.

Crack for noteworthy composer 2 crack