American Top 40

American Top 40 (previously 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 (a division of iHeartMedia). 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. 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. GEICO is the main sponsor for the show.
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 had spent nine years hosting his own countdown Casey's Top 40 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.
Currently, 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. However, there is no distinction made between the two shows on air. There are also two classic editions of the original AT40 distributed every weekend, featuring past Kasem-hosted shows from the 1970s and 1980s.
In its early years, AT40 used the Billboard charts to compile the countdown, touting it as "the only source". The program subsequently switched to being based on Radio and Records airplay data upon its late 1990s return, until R&R was folded into Billboard in 2009. The current source for the AT40 charts are unpublished mainstream Top 40 and hot adult contemporary charts compiled by Mediabase.
In October 2021, the show stopped using the AT40 abbreviation and now uses its full name on air. Despite this, some affiliates still use the abbreviation when promoting the show.
== Hosts ==
* Casey Kasem (1970-2009)
* Shadoe Stevens (1988-1995)
* Ryan Seacrest (2004-present)
== Guest Hosts ==
=== 1970 ===
* Don Bowman
* Dave Hull
* Gary Owens
=== 1971 ===
* Dick Clark
=== 1972 ===
* Bob Eubanks
* Don Messick
=== 1973 ===
* Wink Martindale
=== 1974 ===
* Jay Stewart
=== 1975 ===
* Robert W. Morgan
=== 1976 ===
* Dave Roberts
=== 1977 ===
* Charlie Van Dyke
=== 1978 ===
* John Belushi
=== 1981 ===
* Pat O'Brien
=== 1982 ===
* Chevy Chase
* Hall & Oates
=== 1983 ===
* Dan Aykroyd
* Regis Philbin
* Bill Wendell
=== 1984 ===
* Sonny Melendez
=== 1985 ===
* Christopher Guest
* Tim Matheson
=== 1986 ===
* Phil Hartman
* Charlie Tuna
=== 1987 ===
* Victoria Jackson
* Frank Welker
=== 1988 ===
* Markie Post
* Paul Rodriguez
=== 1989 ===
* Harry Anderson
* Jane Curtin
* Jack Wagner
=== 1990 ===
* John Davidson
=== 1991 ===
* Jan Hooks
* Richard Marx
=== 1992 ===
* Billy Crystal
* Mark Elliott
* Alex Trebek
=== 1993 ===
* George Carlin
* Dana Carvey
=== 1994 ===
* Gilbert Gottfried
* Steve Harvey
* Donny Osmond
=== 1995 ===
* Jim Breuer
=== 1996 ===
* Gordon Elliott
=== 1997 ===
* Julia Louis-Dreyfus
=== 1998 ===
* Jim Belushi
* Darrell Hammond
=== 1999 ===
* Nora Dunn
=== 2000 ===
* Wayne Brady
* Brian Doyle-Murray
=== 2002 ===
* Five for Fighting
=== 2003 ===
* Joe Cipriano
* DL Hughley
=== 2004 ===
* Billy Ray Cyrus
* Jennifer Lopez
=== 2005 ===
* Christina Aguilera
* Christine Ebersole
* David Koechner
=== 2006 ===
* Pamela Anderson
* Rachel Dratch
=== 2007 ===
* Holly Robinson Peete
* Britney Spears
=== 2008 ===
* Mariah Carey
* Coldplay's Chris Martin and Jonny Buckland
* Craig Ferguson
* Janeane Garofalo
* Brody Jenner
* Chris Kattan
=== 2009 ===
* Kris Allen
* Joan Cusack
* Gavin DeGraw
* Pat Monahan
=== 2010 ===
* Nick Cannon
* Sean Combs
* Hilary Duff
* Neil Patrick Harris
* Jesse McCartney
* John Schneider
* Sherri Shepherd
* Taylor Swift
* Rob Thomas
=== 2011 ===
* Margaret Cho
* Chris Elliott
* George Lopez
* Jessica Simpson
=== 2012 ===
* Donald Faison
* Will Ferrell
* Kesha
* Nick Lachey
* Mario Lopez
* Jenny McCarthy
* Katy Perry
=== 2013 ===
* Fred Armisen
* Kelly Clarkson
* Selena Gomez
* Taran Killam
* Kellie Pickler
* Ryan Tedder
=== 2014 ===
* Steve Carell
* Sabrina Carpenter
* Jason Derulo
* Robert Downey Jr.
* Tina Fey
* Andy Grammer
* Leslie Jones
* Joel McHale
* Pitbull
* Amber Riley
* Ashley Tisdale
=== 2015 ===
* Vanessa Bayer
* Colin Jost
* Jimmy Fallon
* Will Forte
* Demi Lovato
* Anthony Ramos
* Meghan Trainor
=== 2016 ===
* Abby Elliott
* Bill Hader
* Joe Jonas
* Kevin McHale
* Charlie Puth
=== 2017 ===
* Beck Bennett
* DNCE
* Lady Gaga
* Ariana Grande
* Anthony Michael Hall
* Adam Lambert
* Billy Porter
=== 2018 ===
* Alessia Cara
* The Chainsmokers
* Fergie
* Ana Gasteyer
* Lucy Hale
* Shawn Mendes
* Mandy Moore
* Ed Sheeran
* Hailee Steinfeld
=== 2019 ===
* 5 Seconds of Summer
* Miley Cyrus
* Scott Evans
* Michael Fitzpatrick
* Niall Horan
* Nick Jonas
* Bebe Rexha
* Timbaland
=== 2020 ===
* Noah Cyrus
* Liza Koshy
=== 2021 ===
* Michael Strahan
* Josh Robert Thompson
* Pete Wentz
=== 2022 ===
* Ben Platt
* Shaggy