American Top 20 with Casey Kasem

American Top 40

American Top 40 logo as of 2015.
Genre	Music chart show, talk
Running time	4 hrs. (including commercials) 3 hrs. + 15 min. (w/out commercials)
Country of origin	United States
Syndicates	Premiere Networks
Hosted by	Ryan Seacrest (2004–present) Casey Kasem (1970–88, 1998–2004) Shadoe Stevens (1988–95) various guest hosts
Announcer	Kelly Doherty Dave Foxx
Created by	Casey Kasem, Don Bustany, Tom Rounds and Ron Jacobs
Produced by	Easton Allyn
Original release	July 4, 1970 – present (hiatus January 28, 1995-March 28, 1998)
Website	www.at40.com

American 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. The program is currently hosted by Ryan Seacrest and presented as an adjunct to his weekday radio program, On Air with Ryan Seacrest.

Originally a production of Watermark Inc. (later a division of ABC Radio known as ABC Watermark, now Cumulus Media Networks), AT40 is now distributed by Premiere Networks in the United States, Canada, Australia, the United Arab Emirates, Singapore, China, India, Sri Lanka, Indonesia, Oman and several other territories worldwide. It can also be heard on both the iHeartRadio application and the AT40 Mobile application on mobile smartphones and tablets as well as on Xbox 360, Xbox One consoles and the Armed Forces Network.

Co-creator Casey Kasem hosted the original AT40 from its inauguration on July 4, 1970 until August 6, 1988. Shadoe Stevens took over the program on August 13, 1988 and hosted until January 28, 1995 when the original program came to an end. Three years later, Kasem teamed up with Premiere's predecessor AMFM Radio Networks to relaunch AT40. Kasem, who spent nine years hosting his own countdown for Westwood One, returned to hosting his creation on March 28, 1998. Seacrest took over AT40 on January 10, 2004 following Kasem's retirement from the series.