<p>American Top 40 (commonly abbreviated to AT40) is an internationally syndicated, independent radio program created by Casey Kasem, Don Bustany, Tom Rounds and Ron Jacobs. Originally a production of Watermark Inc. (later a division of ABC Radio, now Citadel Media), it is now distributed by Premiere Radio Networks in the United States, Canada, Australia, the Philippines, Singapore, China, India, the United Kingdom, Malaysia and several other territories worldwide. It can also be heard on Xbox Live via their iHeartRadio application.
Co-creator Casey Kasem hosted the original AT40 from its inauguration on July 4, 1970 until August 6, 1988 and returned to host the revived version from March 28, 1998 to January 3, 2004. (For much of the interim, he hosted the competing Casey's Top 40.) Its other two regular hosts have been Shadoe Stevens (1988–1995) and current host Ryan Seacrest (since 2004) Currently, AT40 with Seacrest airs in two different formats - one for Contemporary Hit Radio and one for Adult Contemporary (formerly Hot Adult Contemporary) stations - with no on-air differentiation other than the charts themselves. Kasem is still heard in two weekly replays of vintage shows from</p>