1970–88: First Casey Kasem era

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. 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. In this hour at No. 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!^[2][3] Now, on with the countdown!

— Casey Kasem at the beginning of the inaugural AT40 broadcast

American 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.^[4] Billboard reported prior to the release of the show that it had been sold to stations in 10 radio markets.^[5]

The chart data broadcast actually included the top 40 songs from the week ending July 11, 1970. The first show featured the last time both Elvis Presley and The Beatles had songs simultaneously in the Top 10.^[6] 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.^[7] In early 1982, Watermark was purchased by ABC Radio and AT40 became a program of the "ABC Contemporary Radio Network". The program was hosted by Casey Kasem and co-created by Kasem; Don Bustany, Kasem's childhood friend from Detroit, MI;^[8] radio veteran Tom Rounds; and 93/KHJ Program Director Ron Jacobs, who produced and directed the various production elements. Rounds was also the marketing director; the initial funder was California strawberry grower Tom Driscoll.

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. The producing staff expanded to eight people, some of them still in the business: Nikki Wine, Ben Marichal, Scott Paton, Matt Wilson, Merrill Shindler, Guy Aoki, Ronnie Allen, and Sandy Stert Benjamin. (Bustany retired from AT40 in 1989; beginning in 1994, he hosted a political talk show on listener-sponsored KPFK.) By the early 1980s, the show could be heard on 520 stations in the United States^[9] and at its zenith, the show was broadcast on 1,000-plus stations in some 50 countries. In the 1980s, it aired in the United Kingdom on Signal Radio,^[10] DevonAir,^[11] Radio 210,^[12] County Sound,^[13] Chiltern Radio,^[14] Radio Tees,^[15] Saxon Radio^[16] and Fox FM^[17] and was also transmitted on Manx Radio.^[18] Kasem told the New York Times in 1990 "I accentuate the positive and eliminate the negative. That is the timeless thing."^[19]

1988–95: Shadoe Stevens era

In 1988, Kasem left the show over contract concerns with ABC and signed with Westwood One to host a competing weekly countdown. Industry trade paper Billboard magazine reported that the main disputes between Kasem and Watermark/ABC were over his salary (which Westwood One tripled upon his signing), because of declining ratings and a smaller group of stations airing the show. Casey's final AT40 show, the 940th in the series, aired on August 6, 1988. At no point during that final show did Kasem ever let on that any changes were afoot. However, he closed the show by telling the audience to catch him on the television show America's Top 10 and did not plug the following week's AT40 (since December 19, 1987, he had always plugged both during his signoff). The #1 song during Casey's final show in the original AT40 era was "Roll with It" by Steve Winwood.^[25] The Moody Blues were the only artist included in both Casey's first and last countdown of the original show.

Kasem was replaced by Shadoe Stevens, whose first American Top 40 show aired on August 13, 1988, on 1,014 stations.^[26] To introduce Stevens to the audience, a two-minute cold open was recorded to start the show with Stevens making his way to the studio through the show's fictitious hall of history; Kasem was mentioned during the course of the open, as a "giant marble statue" of him helped guide Stevens to the studio. The change did not do much to stem the decline as loyal listeners did not take to Stevens as they had to Kasem.

Later, Stevens and AT40 lost a significant number of affiliates when, on January 21, 1989, Kasem's Westwood One show launched. The program, titled Casey's Top 40, used the weekly chart survey published by Radio & Records ("R&R", which is based on radio airplay) instead of the Billboard Hot 100 chart AT40 was still using (which at the time was based on record sales). Further complications arose when some stations that stayed with Stevens also added Kasem's new show.

In an attempt to win back an audience, AT40 tried new features, including interview clips, music news, top 5 flashbacks, and previews of upcoming chart hits (called the "AT40 Sneek Peek"^[27]). It also stopped using the Hot 100 chart, switching first to the Hot 100 Airplay chart and finally to the Mainstream Top 40 chart. Later still, the countdown would use what was called a "No Nuttin'" gimmick that drew criticism; at various points of the show, a song would start immediately after the jingle for its position on the chart was played and Stevens would not offer any commentary until it concluded.^[28]

ABC kept American Top 40 in its syndication lineup despite the continued lack of improvement in ratings, but in 1994 the network finally decided to cut its losses.^[29] ABC announced that after the July 9, 1994 edition of the program, it would be dropping AT40 from its lineup and replacing it with Rick Dees Weekly Top 40.^[30] The move resulted in AT40 completely disappearing from United States radio, as no network picked it up for distribution domestically. Despite this, AT40 did not end production. Radio Express, the show's international distributor, kept the program alive for the overseas markets that had not dropped the series after ABC's cancellation.^[31]

On the weekend of January 28, 1995, the final episode of the original AT40 was broadcast. The final segment of the program, as was the case for many episodes over the previous years, began with the playing of the #2 song on the chart for that week, which was "Another Night" by Real McCoy. This was followed by the final Long Distance Dedication, which was a personal dedication by Stevens to all of the fans of AT40. After thanking the listeners for their support over the previous 24 years, and describing the thought process that went into his decision, Stevens played James Brown's 1991 R&B hit "(So Tired of Standing Still We Got to) Move On".

Finally, Stevens revealed how many different songs had topped the chart over the course of AT40's run, with the final total being 522. The last of these, which was trading places with "Another Night" for this particular week, was "On Bended Knee" by Boyz II Men. This was not the final song to be played; after reading the credits and signing off for the last time, Stevens closed the show by playing, perhaps appropriately, "Happy Trails".

1998–2004: American Top 40 returns; second Casey Kasem era

Two years later, in 1997, two separate and coincidental series of events would lead not only to the revival of American Top 40, but would also see the return of Casey Kasem to host it.

When Kasem left ABC Radio in 1988, the branding still belonged to him and show co-creator Don Bustany through their joint production company. In order to continue using the name after Kasem's contract with ABC Watermark expired, ABC would pay Kasem and Bustany a licensing fee. If, at any point in the future, AT40 was to be cancelled, ABC could retain the licensing rights as long as either a revival was attempted under the company's watch, it produced some sort of special edition of AT40, or made some effort to use the branding as a promotional tool; if they did not do this within a certain period of time, the agreement would be considered to have lapsed and ABC would no longer be able to license the brand. Since ABC did not meet any of the above requirements, and since Bustany departed from AT40 shortly after Shadoe Stevens took over and opted not to have any further involvement with the program, Kasem received full rights to the branding after the agreement lapsed later in 1997.^[32]

Meanwhile, Kasem's contract at Westwood One was due for renewal and the relationship between the two sides was becoming contentious. After Kasem's initial contract expired in 1993, Westwood One renewed it for four more years. Kasem had launched an adult contemporary countdown in 1992 as a companion to Casey's Top 40 called Casey's Countdown, and in 1994 he added a third countdown for hot adult contemporary stations titled Casey's Hot 20.

Things were not all positive, though. Westwood One had been acquired by Infinity Broadcasting Corporation in 1993, which put Kasem in the same fold as radio personalities such as Howard Stern. Then, in 1996, Infinity Broadcasting was purchased by CBS. Kasem grew frustrated that no effort had been made to cross promote his shows over CBS’ airwaves, and had also complained that he was not given as much promotion as he initially had been getting when he joined up with Westwood One in 1989, especially now that he was hosting three weekly programs for the network instead of one. Westwood One, meanwhile, did not feel that Casey's Top 40 was producing as much advertising revenue as it had been when Kasem's contract was up for renewal four years earlier; the program did not have as many affiliates by 1997 as it had in 1993, and the two largest media markets (New York and Los Angeles) had dropped the program several years earlier. Another sticking point between the two sides, other than Kasem's salary demands, was that Westwood One was not willing to let Kasem change the name of Casey's Top 40 to American Top 40.

The sides eventually put aside their differences, with Westwood One deciding that losing Kasem to a competitor was not worth their trouble and Kasem signed on for one more year in December 1997. However, after the February 21, 1998, edition of his weekend countdowns, Kasem disappeared from the airwaves without notice and, unbeknownst to Westwood One, with no intention of returning to work. ^[33]

Chancellor Media, the media company founded by Roy Masters, and Kasem began negotiations to relaunch AT40 for its newly launched syndication service called AMFM Radio Networks. A deal was finalized shortly after Kasem's abrupt departure from Westwood One where Chancellor would become owners of the AT40 franchise and Kasem would return to his creation as host. Westwood One was not happy with this development and filed a breach of contract lawsuit against Kasem, who claimed contractual vagueness gave him the right to seek employment elsewhere.

The revival of AT40 premiered the weekend of March 28, 1998, one week after Westwood One finally cancelled the three countdowns Kasem was hosting for them after four weeks without him. Chancellor also brought Kasem's AC countdowns to their network, with both now being branded as American Top 20 (see Spin-off programming below). Masters sold Chancellor/AMFM to Clear Channel Communications (the predecessor of what is now iHeartMedia) in 1999, at which point AT40 and other syndicated shows from AMFM Radio Networks were transferred into Premiere Radio Networks, which continues to syndicate the show as of today.

The resurrected American Top 40 kept the Radio and Records CHR/Pop chart previously used for Casey's Top 40 and was used as the basis for the show for the majority of this period. The only exception was a brief period from October 2000 to August 2001 when an obscure Mediabase chart was used. This chart had a rather ambiguous recurrent rule, which would see songs removed weekly from the chart from as high as No. 10, while that chart also resulted in songs that charted/peaked lower than No. 40 on Radio & Records pop charts to appear on the AT40 charts. By the time Kasem's last show aired, the show had gone back to using Mediabase's charts.

In December 2003, as part of a new deal with Premiere Radio Networks, Kasem announced that he would retire from hosting American Top 40 so he could focus on his duties hosting Hot AC and AC versions of the show, American Top 20. He also announced that the new host of AT40 would be Ryan Seacrest, an afternoon DJ host from KYSR who was rapidly gaining stardom from his hosting of the successful music reality TV show. American Idol.^[34]

Kasem's last show as host of AT40 aired on the weekend of January 3/4, 2004. His final No. 1 was Outkast's "Hey Ya!", which hit the top of the chart on the weekend of December 13, 2003.^[35]

2004–present: Ryan Seacrest era

The first Ryan Seacrest era logo used from 2004 to 2014.

On January 10, 2004, American Idol host Ryan Seacrest took over the hosting duties of American Top 40 from Kasem, although Kasem would continue to host American Top 20 and American Top 10 until his retirement in July 2009.^[36] With the host change, AT40 underwent a makeover, using a new theme song and introducing several new features. These extras included interviews with celebrities (which were not restricted to musical or countdown artists), a gossip section, and an update on movies screening in cinemas. Other extras inducted on a regular basis include "AT40 Breakout", a song predicted to crack the chart within the next few weeks (formerly known as the "Out of The Box" hit); "AT40 On The Verge" (an expansion of the AT40 Breakout; formerly known as the "Subway Fresh Buzz Song"), songs that are close towards entering the chart, many of which holding the position for multiple weeks; "Request Line", a segment in which Ryan Seacrest will play a song requested by a listener; "Double Play", a former hit from the artist just played; "AT40 Sleaze" (inspired by the "Dees Sleaze" segment of the Rick Dees Weekly Top 40 radio show); and "AT40 Rewind", a hit song from the past decade or so. In between songs, Seacrest and his guest hosts often make deadpan one-liners while writers and producers can be heard laughing frequently, including the security guard "Roger". Additionally, Seacrest initially opened most shows by playing the previous week's No. 1 song, as Kasem often did in the 1980s; this was discontinued after 2006, but in mid-2009 Seacrest began including a shorter recap segment in the show's introduction, in which he would play brief segments of the previous week's top three hits. In December 2004, the Hot AC version of the show debuted, giving both Seacrest and Kasem competing countdowns in the same format until 2009.

The show also began using a new chart that used no recurrent rule. On the first show with Ryan Seacrest, this led to several older songs reappearing after having dropped off many weeks earlier. Over the long term, it meant songs could spend long runs for about a year on the chart even after they went to recurrent status on other published charts. "Here Without You" by 3 Doors Down set a longevity record in 2004 for the CHR show by lasting 50 weeks before finally falling off. In 2006, "Scars" by Papa Roach would go on to tie the record. In 2011, Taio Cruz set AT40's all time longevity record with his song "Dynamite". This hit remained on the chart for 72 weeks, from July 2010 to November 2011. On the Hot AC version of AT40, "Use Somebody" by Kings of Leon set the all-time record in 2011 at 117 consecutive weeks. American Top 40 also became more interactive, involving online song voting and e-mail. In December 2006, the series' website was revamped, and the online song voting was discontinued in favor of publishing the Hot AC chart. The website also includes a toll-free number where fans can make requests and "shoutouts", as they would to a local radio station, and by 2009 replayed clips of shoutouts became part of the show. Online song voting was later reinstated, with results of votes on American Top 40's website factored into the chart rankings. AT40 was also expanded to social media through Twitter and Facebook where listeners from around the world will request a song to be included in the AT40 Extra segment, as well as their own mobile application which is available for free download on the Apple AppStore for iOS devices and on Google Play for Android devices.

Seacrest in 2013.

In March 2010, Premiere Radio Networks announced that "American Top 5," a condensed daily top-5 countdown, would begin airing as part of the daily radio program On Air, also hosted by Seacrest.^[37]

In March 2016, the show underwent some minor changes. "Tell Me Something Good", a segment from Seacrest's weekday show On Air, was added to American Top 40. Additionally, any "extra" songs that aired during the show are announced by Seacrest before playing. The following month, the show resumed mentioning some of its affiliates around the world during the show.

When Seacrest was named the new co-host of Live with Kelly on May 1, 2017, he began to host the show from WHTZ in New York. Another studio near the Live with Kelly set was set up for On Air. Various guest hosts, however, will continue to do hosting duties from its original Hollywood studios when Seacrest is not around.

In February 2018, the show introduced new jingles with new voiceover artists replacing Dave Foxx and Kelly Doherty, who departed iHeartMedia (Premiere's parent company) in January.

In March 2020, amid the COVID-19 pandemic, Seacrest started to host AT40 from his house; the show also included pre-recorded messages from artists thanking healthcare workers and encouraging listeners to stay home, practice social distancing, and to keep in touch with loved ones.

New logo presented for the 50th anniversary.

In August 2020, the show rebranded their logo for the 50th anniversary. It features lines similar to those on the edges of vinyl records. It was changed again in September 2021; ^[38] the same month, Premiere announced the show had been renewed through 2025 with Seacrest as host.^[39]

As of 2020, American Top 40 is produced by Easton Allyn and Jennifer Sawalha, and engineered by James Rash.

AT40 flashback

From December 2000 to December 2002, many radio stations aired reruns of 1980–88 episodes under the title American Top 40 Flashback. The show was syndicated by Premiere Radio Networks. In its early weeks the shows were the original four-hour format of an American Top 40 episode, but after the first month and a half the show was reduced to three hours. Although the national syndication of American Top 40 Flashback ceased in December 2002, radio station WMMX in Dayton, Ohio, continued to carry American Top 40 Flashback on Saturday mornings until the premiere of Casey Kasem's 'American Top 40: The 80s.

Casey Kasem's American Top 40—the 70s and 80s

On August 4, 2006, XM Satellite Radio began replays of the original 1970s and 1980s AT40 shows with Casey Kasem that were digitally remastered from the original vinyl LPs and open-reel master tapes by Shannon Lynn of Charis Music Group. The event began with a weekend long marathon of original shows, with AT40 then being added as a regular show on two of XM's Decades channels, "The 70s on 7" and "The 80s on 8". With the merger of Sirius Satellite Radio and XM Satellite Radio, these AT40 shows began airing on both services on November 15, 2008. On the 70s on 7, it replaced the 'Satellite Survey', a Top 30 countdown of 1970s hits, produced by Sirius and hosted by Dave Hoeffel. On the 80s on 8, it replaced 'The Big 40' countdown produced by Sirius and hosted by Nina Blackwood. As of October 11, 2009, Sirius XM replaced the AT40 countdown on 80s on 8 and debuted a revised version of 'The Big 40' countdown now co-hosted by three of the five original MTV VJs: Nina Blackwood, Mark Goodman and Alan Hunter (Martha Quinn was a fourth co-host from 2009 to 2015).

Sirius XM "70s on 7" currently runs AT40 each Saturday at 12 pm with encore broadcasts the following Sunday at 9 am and at 12 midnight (Eastern Time). Most show dates roughly correspond to the current week in real time. A random episode is also featured on J.J.Walker's show on "70s on 7" Thursdays at 9 pm ET. The mix of AT40 episodes being run on XM include the year-end countdowns, which are typically run in two parts: the first half (#100-#51) in one time slot, and then the second half (#50-#1) in the following time slot. The AT40 specials are also part of XM's rotation; for instance, "AT40 Goes to the Movies" aired prior to the 2007 Academy Awards, and on February 24, "The Top 40 Acts of the 80s So Far" aired on XM 80s the first week of July 2007. Also, "The Top 40 Songs of the Disco Era (1974–1979)" aired on Sirius XM "70s on 7" the second weekend of July 2011. As of the weekend of February 11, 2023, the 6am and noon Saturday editions were discontinued and replaced by a single 9am Saturday airing, with the Sunday airing moved to noon Eastern time.

From October through early November 2006, oldies radio station KQQL in Minneapolis/St. Paul, which is owned by iHeartMedia, ran a series of American Top 40 episodes from the 1970s. Aside from one week, when the station attempted to air a four-hour episode from 1979 in the three-hour time slot (resulting in the show getting cut off at No. 11 and the top 10 not being heard), this test run was largely successful. Because of the success, Premiere Radio Networks decided to launch "Casey Kasem's American Top 40: The 1970s" into national syndication featuring the three-hour shows from 1970 to 1978, and the last three hours of shows originally aired from October 1978 through December 1979. (One original four-hour program, first aired in October 1978, was edited into a three-hour program for re-airing in 2007, and the four-hour "Disco Hits" special from July 1979 with the first hour optional was aired in 2008, but until the fall of 2010, no other program from the last 15 months of the 1970s was included in the "AT40: The 70s" package. Starting in late 2010, Premiere began airing three-hour versions of four-hour AT40s from 1978 to 1979, beginning the broadcasts at the start of the countdown's second hour; during the spring of 2012, Premiere began making the first hour of these programs "optional," meaning that stations can choose to air all four hours of the four-hour programs, or just the last three.) Starting in 2012, whenever programs from 1970 to 1972 were scheduled to air, Premiere began offering affiliates the option of airing a later 1970s program instead (typically, a corresponding year from seven years later, or 1977–1979).

The 1980s version premiered on April 8, 2007, replacing the American Top 40 Flashback reruns. The shows are available in either their full original four-hour format, or an abbreviated three-hour version that omits the first hour of the show. To date, the latest program to air as part of the "AT40: The 80s" package has been August 6, 1988 – Kasem's last show with the original program. Because the rights to Shadoe Stevens-era episodes were held by Cumulus Media, no programs from August 13, 1988, to 1995 have been re-aired as part of this or any similar block.

To date, the only re-aired classic AT40 programs that featured a host other than Kasem are the shows of March 25, 1972, with Dick Clark as host; September 12, 1981, with Gary Owens as host; and May 13, 1978, and July 17, 1982, both with Mark Elliott as host. All were aired as tributes after Clark's, Owens' and Elliott's deaths, respectively.

Newly produced extra segments hosted by voiceover talent Larry Morgan are available for use at stations' discretion. Prior to Casey leaving Premiere Radio, these segments were hosted by his son Mike; when the series first began, these segments were hosted by one of Casey's former guest hosts, Ed McMann. These extra segments are also heard on the 80s show. KQQL was the first to sign on, airing programs beginning on December 30, 2006. Typically, the "optional extras" were songs that had yet to enter the top 40 of the Hot 100. However, some songs never reached the top 40 but had since become popular at classic hits/oldies/classic rock stations or certain novelty songs that were popularized by certain media events like the Who shot J.R.? cliffhanger (recorded by Gary Burbank) and the Chicago Bears 1985–86 NFC win and the team itself recording a rap tune about going to the Super Bowl, while others were tributes to performers who had just died. For early 1970s programs, some of the "optional extras" were actually extras (i.e., "oldies") that were originally a part of the original program; in this case, Kasem's original commentary and introduction of the song were kept intact, in lieu of Morgan's voiceover.

In March 2008, XM Satellite Radio rebranded the XM broadcasts with the "Casey Kasem's American Top 40" name and logo used for terrestrial broadcasts, although XM still aired the commercial-free broadcasts, while Premiere Radio carries edited and recut broadcasts with commercials. Following the merger of Sirius and XM, the AT40 shows airing on those platforms have occasionally been edited. In some cases, extras and LDDs have been cut from the original broadcasts.

Sirius XM 70s on 7 aired the inaugural AT 40 (which originally aired July 4, 1970) on July 4, 2013, as part of a special July 4 broadcast.

As of 2017, American Top 40: The 70s & 80s are produced by Toby James Petty and engineered by Shannon Lynn, both of whom had been members of the current AT40 production staff prior to Kasem's 2004 departure.

As of 2014, American Top 40: The 70s shows that were originally produced in mono are being converted to true stereo by Ken Martin, a program director and disk jockey for AT40 affiliate WTOJ in Carthage, New York. With some 1970s episodes featuring songs that were originally further edited by Watermark staff, Martin restored those songs to their original broadcast length; many of these extended editions were broadcast exclusively on Martin's station, WTOJ.

As of 2019, shows from the 1970s and 1980s are airing continually, without commercials, on the iHeartRadio station "Classic American Top 40". Most of iHeart's branded stations use an HD Radio subchannel in one of their markets to originate their app-only stations, and in this case, WMMX-HD2 in Dayton, Ohio, carries it over-the-air in that market.

As of December 2023, rebroadcast shows are currently aired on 200 radio stations in 5 countries and every U.S. state except Montana. Foreign rebroadcast shows are heard in four of the eastern provinces of Canada, as well as the American Forces Network, Australia, Berlin, Aruba, and The Cayman Islands.

In Late 2020, Sirius XM began airing an additional AT40 program on Thursday nights, presented as a random choice and not necessarily tied to the specific weekend. Included in this series were guest-host appearances from Dave Hull (a 1971 episode - the first AT40 to have a guest host - aired on November 12, 2020 to note Hull's recent passing) and Wink Martindale (a 1975 episode, airing on January 7, 2021).

Billboard magazine

AT40 used the top 40 songs from the Billboard Hot 100 singles chart from the show's inception in 1970 to November 23, 1991. The chart was widely regarded as the industry standard for tracking the popularity of singles, and was thus a natural choice to be used. Kasem would frequently announce during the show that Billboard was the only source for the countdown. While using these charts worked well for the first half of the 1970s, as music changed during the decade and disco became popular on the charts, some rock stations began to drop the show because of complaints from program directors that AT40 was playing too many songs not normally heard on their stations.

This gradually became a wide schism as rock splintered into several formats in the early 1980s. As a result, AT40's weekly playlist could be very diverse in the styles and formats of the songs played. Historians have noted that no one station actually played all of the songs on the Billboard Hot 100 list, because they represented overlapping formats, such as hard rock, mainstream rock, heavy metal, dance, new wave, punk, rap, pop, easy listening/adult contemporary and country. Stations tended to specialize in only one or two of these formats and completely ignore the others.

One solution for the AT40 producers was to air frequent specials (at least three or four times a year) that concentrated on the classic music of the past, such as Rock in the Movies and Top Hits of the Seventies. But as Top 40 stations evolved into CHR, they began to avoid syndicated shows like AT40, preferring to stick with their own special niche formats.

By the early 1990s, many singles, mostly of the rap, heavy metal or grunge genres, reached the chart based on strong sales despite low airplay; several were very long, others were too controversial or risqué for mainstream airplay (for instance, the sexually explicit "Me So Horny" by 2 Live Crew made it to No. 26 on the Hot 100 in 1989). These songs would generally only be aired in brief snippets during the show.

Because of this, American Top 40 switched to the Hot 100 Airplay chart (then known as the Top 40 Radio Monitor). These songs generally scored much higher radio airplay, and some were not even released as singles (such as "Steel Bars" by Michael Bolton). During this time, a few songs made very high debuts, including two that almost debuted in the No. 1 spot: "I'll Be There" by Mariah Carey, which entered at No. 4, and "Erotica" by Madonna, which entered at No. 2.

In January 1993, American Top 40 switched charts again, this time to the Billboard Top 40 Mainstream chart. This chart had more mainstream hits but fewer urban, dance and rap songs.

AT40 did not always use the official year-end Billboard chart during the 25 years in which the show used Billboard charts. In 1972, 1973 and 1977, as well as 1980–1984 and 1990–1994, AT40 compiled its own year-end chart. These charts were often close to Billboard's, but AT40 would use a mid-December to early-December time period while Billboard's survey year varied from year to year. AT40 matched Billboard's No. 1 year-end song every year except 1977, 1984, 1990 and 1993.

Radio and Records magazine

With the show's revival in 1998, a new chart was implemented, the top 40 portion of Radio and Records CHR/Pop top 50 chart, which was already in use on Casey's Top 40. This chart used a recurrent rule that removed songs below No. 25 that had exceeded 26 weeks in the top 50; these removals, if they occurred in the top 40, would be reflected on the appropriate week's program. In 1999, the rule was modified to further restrict long chart runs: songs falling below #20 with at least 20 weeks in the top 50 would now be removed.

On October 21, 2000, American Top 40 began using an unpublished chart on a weekly basis for the first time in its history. The chart seemed to be a variant of the CHR/Pop chart provided by Mediabase, the data provider to Radio & Records. The most noticeable feature of this new chart was its ambiguous recurrent rule. Songs would be removed regularly from within the top 15, seemingly regardless of the number of weeks they had spent on the chart. Additionally, the chart has resulted in songs that otherwise peaked at #41–50 on R&R's charts appearing on the AT40 charts. This chart lasted until August 11, 2001, when AT40 returned to the Radio & Records pop chart. The return coincided with another modification in the recurrent rule; songs would be removed below No. 25 after three consecutive weeks without a bullet (an increase in radio plays). This change would be short-lived, as in November 2001, Radio & Records returned to the 20 weeks/below No. 20 rule, which remained in place for the remainder of Kasem's tenure.

Adult Contemporary countdowns

When Casey Kasem joined what was then AMFM Radio Networks, he had been doing two weekly countdowns for adult contemporary formatted stations. Both of these shows would find a home with him at his new syndicator and were rebranded once he joined. Both shows took the name American Top 20 (AT20) and launched the same weekend as Kasem's new AT40. He would concurrently host both shows with AT40 until he handed the show over to Ryan Seacrest in January 2004, then continue as host of the AC countdowns until he retired in 2009. After Kasem retired, the Hot AC American Top 20 and the Adult Contemporary American Top 10 were discontinued.

In December 2004, Premiere Networks launched a version of Seacrest's AT40 for the same hot adult contemporary stations that AT20 had been targeting. Although such a move made AT20 redundant, Premiere continued to offer Hot AC countdowns hosted by both Kasem (AT20) and Seacrest (AT40) from December 2004 thru July 2009.

Television spinoff

From 1980 to 1992, a video version of the show entitled America's Top 10 was aired in syndication to television stations across the United States. Kasem hosted this version from 1980 to 1989. When Kasem left American Top 40 in 1988, he remained as host of America's Top 10 until the end of 1989, when he would be replaced by Siedah Garrett and later Tommy Puett. Kasem returned by 1991, and the show ran until 1992.

Other formats

Based on the success of American Top 40, Kasem and Don Bustany created a spinoff top 40 countdown for Watermark for Country Radio called American Country Countdown, patterned after Kasem's program. "ACC" premiered in 1973, and was hosted by Don Bowman from its inception until April 1978. Bob Kingsley replaced Bowman and hosted until the end of 2005, after which Kix Brooks of the late country music duo Brooks & Dunn took over; Brooks has been hosting ACC since. Kingsley later moved to another program, Country Top 40 (abbreviating, not coincidentally, as "CT40"), which follows the same format as AT40 and ACC; Kingsley died on Thursday, October 17, 2019. Both ACC and CT40 remain on the air: ACC on Westwood One and CT40, now hosted by Fitz, syndicated by Hubbard Broadcasting.

After Kasem left ABC, the network launched American Gold, a spinoff oldies countdown (featuring far fewer songs, and often focusing on a particular artist) hosted by Dick Bartley. American Gold's last show aired at the end of March 2009, replaced with another show hosted by Bartley for United Stations Radio Networks, Classic Countdown.

The American Top 40 format was adapted in an Australian show titled Take 40 Australia, similarly counting down the top 40 songs in the country.

Offensive content

The first song to receive this advisory was in April and May 1971, with a spoken word piece, "The Battle Hymn of Lt. Calley", by Terry Nelson and C-Company.^[43][44] Some better-known songs which received this treatment included "Kodachrome" by Paul Simon, "Roxanne" by The Police, "Ain't Love a Bitch" by Rod Stewart, and "Paradise by the Dashboard Light" by Meat Loaf.

Perhaps the most infamous of these songs was Chuck Berry's number-one hit "My Ding-a-Ling", which put some stations in the odd position of having to air AT40 without playing the number one song; at least one station, KELI in Tulsa, Oklahoma, censored out the song at its No. 1 position, replacing it with a message from station management, explaining why they chose to censor the program.^[45] The censorship of this song continued even into the twenty-first century; some stations, such as WOGL in Philadelphia, replaced this song with an optional extra when it aired a rerun of the November 18, 1972, broadcast (where it ranked at #14)^[46] on December 6, 2008.

In the summer of 1977, radio station KRNQ in Des Moines, Iowa, edited out "The Killing of Georgie" by Rod Stewart, because of the subject matter of a homosexual being murdered; that song peaked at No. 30 on the countdown.

In 1978, when Billy Joel's "Only the Good Die Young" (wherein Joel urged pre-marital sex by a teen Catholic girl, Virginia) was on the charts, AT40 had placed warnings in shipments to warn affiliates in highly Catholic populated areas along with a special break in the countdown for stations to substitute another song in its place. The affiliates usually used the suggestion, though some did not and no major complaints were ever heard. (Many of these memos have been reprinted in Pete Battistini's book, "American Top 40 with Casey Kasem: The 1970s".)

In situations where a charting song contained offensive language and the record company was unable to provide AT40 with a clean edit of the song, the producers would often make an edit themselves. Such was a case with Bob Dylan's Top 40 single, "George Jackson", which peaked at #33 in January 1972 and appeared for two weeks on AT40. The offensive lyric in the song was, "He wouldn't take shit from no one." To rectify the problem, AT40 engineer Bill Hergonson edited the lyric, which was now heard as "He wouldn't take it from no one."^[47] A similar situation occurred again in July 1975, when The Isley Brothers' "Fight the Power" was in the Top 40, but in this case, the substitute version provided by the group's label was unsuitable, resorting to the engineer to substitute grunts and extra drum beats over the offending parts of the original record. However, this was not before AT40 erroneously played the uncensored version (with the lyric "... by all this bullshit goin' down") the first two weeks on the chart, on the July 12 and 19, 1975 editions.^[48]

Songs with offensive words in their titles were often censored for radio airplay, and is reflected in their inclusion on AT40. In 2011, three such songs made it to the #1 position on AT40: "Fuck You" by CeeLo Green (changed to "Forget You"), "Fuckin' Perfect" by Pink (changed to "Perfect"), and "Tonight (I'm Fuckin' You)" by Enrique Iglesias (changed to "Tonight (I'm Lovin' You)"). Other notable songs included "Niggas in Paris" by Jay-Z & Kanye West (becoming "In Paris", peaking at #5), "Ass Back Home" by Gym Class Heroes (became "Get Yourself Back Home", peaking at #12), "I Don't Fuck With You" by Big Sean featuring E-40 (became "I Don't Mess With You," peaking at #34), "Fuck U Betta" by Neon Hitch (becoming "Love U Betta" and peaking at #29; this song was also first played in Subway's Fresh Buzz Song of the Week), and Bella Poarch's "Build a Bitch" (became "Build a B", peaking at #27). On the August 5, 2023 edition of AT40, the song "Keep Dat Nigga" by ICandy (became “Keep Dat”, peaking at #37) was played as a breakout song.

In 2000, "Sexual (Li Da Di)" by Amber and "The Bad Touch" by Bloodhound Gang debuted on AT40 without any censorship despite both songs' context referring to sexual activity. The songs peaked at No. 25 and No. 21 respectively. That same year, the show also used a slightly suggestive version of soulDecision's "Faded" (which peaked at #6), despite a more radio-friendly version of the song being available.

In the 2011 fun. song "We Are Young", the word "higher" is censored from the first verse. Rihanna's "S&M" had the word "sex" censored during its original run and extras, however, when it was played as an extra in 2022, the word was no longer censored.

In the 2012 Bruno Mars' song "Locked Out of Heaven", the word "sex" is censored from the pre-chorus. Similar edits were done to the song "That's What I Like" in 2017, except the word "sex" is censored from the chorus.

In 2015, The Chainsmokers's "Roses" (feat. ROZES), Travis Scott's "Antidote", Halsey's "New Americana", and Alessia Cara's "Here" had been edited by censoring one of their chorus in the lyrics dealt with prohibited drugs. In 2018, Khalid's "Young Dumb & Broke" was similarly censored, with the lyric "I'm so high at the moment" being completely edited out of the song because of references to drugs. However, on some versions of the show, the lyric was not censored.

In 2017, Jason Derulo's "Swalla" (feat. Nicki Minaj and Ty Dolla $ign) also had its chorus heavily censored because the context of the title referred to oral sex. However, the title of the song was announced without being censored, presumably because Ty Dolla $ign uses the title lyric to refer to drinking during his verse in the song.

In 2018, N.E.R.D and Rihanna's "Lemon" was significantly edited. An alternative version of the song was played, which had the final two verses of the song played on loop. This is presumably to remove the first two verses, in which the lyrics included highly charged political issues such as immigration, racism and anti-Donald Trump sentiments.

In recent years, AT40 has played edited versions of songs that are also used on iHeartRadio’s family stations, with many of these edits being different than normal radio edits. In 2019, the chorus of Fletcher's "Undrunk" was edited because of lyrics about masturbation. Later that year, Ed Sheeran and Khalid's "Beautiful People" was edited with the line "Champagne and rolled-up notes" being replaced with the second line in the chorus, as well as Jonas Brother's "Only Human" having the word "drunk" removed/swapped from the chorus. Post Malone's song "Circles" was also edited on the countdown, with one of the phrases in the second verse censored and swapped with extra grunts from the beginning due to the phrase referring to sexual activity. In Blackbear's song "hot girl bummer" the line "one more line I'm superhuman" is removed from the pre-chorus.

In 2020, BENEE and Gus Dapperton's song "Supalonely" was edited because of drinking references in its lyrics. Later that year, Taylor Swift's song "Cardigan" was edited because of drinking references in its lyrics, replacing the word "bars" with "cars", the same thing happened in 2019 with the Jonas Brothers' song "Sucker". Also in that same year Lil Mosey's song "Blueberry Faygo", a version was played in which both the chorus and verses were edited for sexually explicit references.

In 2021, the words 'drug(s)' and 'suicide' were censored in Nessa Barrett and Jxdn's song "La Di Die." Similarly, in Lil Nas X and Jack Harlow's song "Industry Baby", the word "Doobie" is censored from the first verse, along with the second verse of the song, where "handprint on her ass cheek" was edited out and replaced with an instrumental bridge. Also that same year, several words from Doja Cat's "Need to Know" were removed because of references to sexual activity.

In 2022, Charlie Puth's song "Light Switch", the word "dirty" is censored from the first verse. When Gayle's song "ABCDEFU" entered the chart at the beginning of that year, the intro and chorus had been edited, with the first line "A-B-C-D-E-F you" edited to "A-B-C-D-E-Forget you," as well as the phrase "Fuck you" replaced with "forget you" and "fuck off" edited to "get lost". Those edits also appear on the official clean edit of the song, which is titled “abc (nicer)”. At some point between May and June 2022, Becky G's "Mamiii", featuring Karol G, had the word "cuero" (literally "leather", whose meaning in some Latin American countries refers to "prostitute") and the line "rata de dos patas" ("two-legged rat") edited out. Similarly, Pitbull and Lil Jon's "Jumpin" had the word "culo" censored from the chorus (some affiliated stations instead censor the accompanying line entirely during normal programming, for example, former affiliated station D99 in Monterrey, Mexico). Later, in June, Justin Bieber's "Honest", featuring Don Toliver, was played uncensored (as it contained the words "weed", "fuck" and "Pistol Pete", not heard in the clean version). Later in that same year, Yung Gravy's song "Betty (Get Money)" was edited to censor the phrase "I blow her back out" from the lyric "With your baby mama at the crib, I blow her back out", due to the phrase referring to anal sexual activity; however, in some versions this line wasn't censored.

In 2023, SZA’s song "Kill Bill" was edited to censor the words "kill" and "killed". The same edits were also done on the official radio version of the song. Later that year in June, although a clean version of “Never Felt So Alone” by Labrinth was not widely available, American Top 40 played a clean version of the song, but “bottle liquor” from the line “Hollow kiss, bottle liquor” was edited out, due to drinking references; however, when it was played as an "on the verge" track, the phrase wasn't removed, but the word "shit" was. In Lil Durk and J. Cole's song "All My Life", the word "shootin'" is censored from the second verse due to violence. In Bakar's song "Hell n Back", the words "drugs" and "MDMA" are censored in the first verse. In Travis Scott's song (ft The Weeknd and Bad Bunny) "K-pop", the words "meto" and "chingando" are censored in Bad Bunny's verse.

In August 2023, AT40 played the solo version of Doechii's song "What It Is (Block Boy)" without any censorship despite some affiliate stations playing a clean edit that censored the word "ho" from the chorus; however, on the HAC chart, when it was played as an "on the verge" track (weekend of 25 November 2023), the version played for it replaced "ho" with "though". AT40 also initially played the clean solo version of Jungkook's song "Seven" before switching to the original clean version featuring Latto; however, on the HAC chart, it remained with Jungkook's solo version during its entire chart run (even as an extra). In September 2023, Kaliii's song 'Area Codes' had been edited by censoring the word "hoe" from the chorus. In Jungkook and Jack Harlow's song "3D" had the third verse and outro edited significantly. The edited version played had the words "dead body", "whorin" and "shrooms" censored from the third verse and "playin with yourself" was censored from the outro due to masturbatory references. The Kid LAROI's "Too Much" had the word "shrooms" censored from both the first and last verse. Pitbull's song "Freak 54" was edited by backmasking the word "dope" from the first verse. In Doja Cat's song "Agora Hills's the phrase "gun to" was censored from the first verse. In Tiësto and BIA's song "BOTH" the word "gushy" is censored from the first verse. In Jack Harlow's song "Lovin on Me" the words "choke" and "killer" are not censored on the AT40 version, however many affiliates censor the two words.

Unannounced titles

Although Kasem never banned a song from the countdown, there was at least one instance in which the title wasn't always said. When George Michael's "I Want Your Sex" hit the Billboard charts in the summer of 1987, Kasem and a sub host, Charlie Van Dyke occasionally failed to announce the name of the song; only its artist (e.g., "George Michael's latest hit is up five notches this week ..."). There was a few occasions it was said however. Also, as had been done with previous controversial hits, because of the song's suggestiveness, the show's structure was altered slightly, so stations could opt out of the song. This pattern was also evident during the 1987 Year End countdown. The song title was mentioned five times during its chart run (June 20, 1987; June 27, 1987; April 7, 1987; December 9, 1987, and September 19, 1987), during the week-ending episode of September 26, 1987, when it dropped out of the Top 40, and during the Top 100 of 1987 show; Shadoe Stevens, his successor, however did mention the title on the show from July 31, 1993, as part of the Flashback feature, as it was in the top 5 from that week in 1987. In the spring of 1991, when "People Are Still Having Sex" by LaTour and "I Wanna Sex You Up" by Color Me Badd debuted the same week, their titles were announced in full.

Another song that had its title unannounced after its first week was "Me So Horny" by 2 Live Crew, in the fall of 1989 (the Shadoe Stevens era). It was mentioned twice at the beginning of the song, and back announced once, its debut week. For the rest of its chart run, the title was never again mentioned. When 2 Live Crew returned to the top 40 in the Summer of 1990, with "Banned in the U.S.A.", Shadoe did mention that it was the follow-up to "Me So Horny". The song did come with edit out instructions for stations as well. Other songs around that time with edit out warnings were "The Humpty Dance" by The Digital Underground, and "Tic Tac Toe" by Kyper.

In 2018, "God is a Woman" by Ariana Grande had its title not mentioned and its chorus edited in some airings of the show in some Middle Eastern countries, presumably because of religious beliefs; despite this some radio stations such as Hi FM in Oman play the song in its entirety during normal programming.

In 2023, Taylor Swift's "Slut!" was played as a breakout song, but its title was unannounced (with a generic AT40 breakout intro playing beforehand) with Ryan only referring to the song as a breakout from Taylor Swift afterwards; the song itself played unedited with the title remaining intact as part of the chorus; it subsequently debuted at #34 (with Ryan not mentioning the title once again) before falling off the chart after just one week as it was replaced with "Is It Over Now?".

Lengthy songs and double-sided hits

Very rarely was a song on that week's chart excluded from that week's AT40, if so only because of time considerations—on an edition that aired the weekend of December 19, 1970, The Guess Who's "Share the Land", which ranked at No. 30 that week, was omitted from AT40, to play both sides of that week's No. 1 Double A-side hit, George Harrison's "My Sweet Lord" / "Isn't It a Pity".^[49] Normally when a Double A-side appeared on the charts, one side was played one week, with the other played the next week, alternating each week as long as it was in the Top 40. Similar omissions occurred in February 1974 when both the Gordon Sinclair and Byron MacGregor versions of The Americans simultaneously hit the Top 40; in each case, only one version was played each week alternately.

Don McLean's 1971 hit American Pie, which was 8:33 long, was split into two segments for the single release. When the song aired on AT40, they usually played a promo edit which ran around 4:20, with the entire song played when it reached No. 1 and on another occasion when it was dropping off the charts.

In early 2013, Justin Timberlake's single "Mirrors" had to be edited for time, as the song is over eight minutes long.

In 2017, Harry Styles' single "Sign of the Times" was also edited for time. The original song is over 5 minutes long.

In 2021, AT40 played the original version of Billie Eilish's single "Happier Than Ever", which is 4:58 long, although most affiliates played the radio version, which is 3:09 long.

In 2022, Steve Lacy's "Bad Habit" was played in its original length of 3:52, while the radio edit, played by a good amount of affiliates, is 2:45 long, skipping the outro.

Remixes and alternative versions of charted songs

On several occasions, the show would play remixed versions of charted songs. Notable examples included Enya's "Only Time", LeAnn Rimes' "Can't Fight the Moonlight", Mikaila's "So In Love With Two", Whitney Houston's "It's Not Right but It's Okay" and "My Love Is Your Love" among others.

In 2001 and 2002, AT40 played the original versions of Joe's "Stutter", Jennifer Lopez's "I'm Real" and Samantha Mumba's "Baby Come on Over", in which airplay was given for remixed versions of each song.

Some time during its run on the CHR chart, AT40 aired (and still airs as an occasional extra) the Tiësto remix of John Legend's All of Me, despite some affiliates airing the original 4-minute song.

In 2018, AT40 played the original version of Halsey’s "Alone", despite the remix version featuring Big Sean and Stefflon Don receiving airplay.

In 2019, AT40 played the original version of Lil Nas X's "Old Town Road", despite the remix version with Billy Ray Cyrus receiving airplay.

During a portion of its run in 2020, AT40 played the Arty remix of Surf Mesa's "ily", despite most of its affiliates airing the original version; it was eventually switched to the original version when the song entered the HAC chart.

In 2021, AT40 played the original version of All Time Low's "Monsters", despite the remix version with Blackbear and Demi Lovato being serviced to Top 40 radio, while the original version was serviced to Alternative rock stations. Later that year, AT40 continued to play the original version of The Weeknd's "Save Your Tears" (released in 2020), despite some affiliates playing the remixed version with Ariana Grande on Top 40 radio when it was released in April of that year.

When Dua Lipa’s song "Levitating" first hit AT40 in October 2020, the remix version featuring DaBaby was played as it was sent to Top 40 stations. However, after DaBaby made controversial comments at Rolling Loud Miami in late July 2021, many radio stations replaced the remix version of "Levitating" with the original solo version that was already on Future Nostalgia with AT40 following suit in the week-ending August 7, 2021, edition (although this did not affect the HAC chart as it was already playing that version); in addition, his verse was also edited out from DJ Khaled’s song "I Did It". Almost two years later on the week-ending March 5, 2023 edition, AT40 played the solo mix of "Camila Cabello"'s song "My Oh My", removing his verse on the CHR edition as an optional extra, though it didn't affect HAC as it already played that version during its original run.

In late 2021, American Top 40 played the original version of Wizkid’s song "Essence", featuring Tems, despite the remix version featuring Justin Bieber receiving airplay on some affiliates.

In 2022, American Top 40 played the solo version of Imagine Dragons' "Enemy", even though most affiliates played the original version featuring JID, although the solo version is more commonly played on affiliates in the Asia-Pacific region. In the same year, AT40 played the no rap edit of Ed Sheeran’s "2step" even when many affiliated stations played the original version featuring Lil Baby. Also in the same year, AT40 played the original version of Stephen Sanchez's "Until I Found You", despite some affiliates playing the remix featuring Em Beihold.

In 2023, despite the release of the remix version of the song with Ariana Grande on February 24 that year, American Top 40 still continued to play the original version of The Weeknd’s "Die for You," which was originally released in late 2016 and entered the chart in late 2022. In March 2023, American Top 40 played the original version of PinkPantheress's "Boy's a Liar", although many affiliates play the remix version of "Boy's a Liar Pt. 2" featuring Ice Spice (the show did play the remix at one point, only to revert to the original version before later switching to the remix version again a few weeks later, but then switched back to the remix by popular demand). This also happened with Charlie Puth's song "That's Not How This Works", featuring Dan + Shay, despite some stations playing the remix version with Sabrina Carpenter (who also at the time had a remix of "Nonsense" with Coi Leray). Metro Boomin's "Creepin" had 21 Savage's line removed from the HAC chart (the same would latter happen with the Kid LAROI's "Too Much", as Central Cee's line was removed from this version's chart, though it was later played during Jelly Roll's guest hosting on the weekend of 16 November 2023).

In May 2023, American Top 40 played the original version of "Karma" by Taylor Swift, despite the remixed version featuring Ice Spice later receiving airplay.

American Top 40 still played the original version of "Kill Bill" by SZA, (which entered the chart in January 2023), despite the remix featuring Doja Cat, (which was released on April 14, 2023) receiving airplay on some affiliates.

In June 2023, AT40 played the original version of Fifty Fifty's "Cupid" on the CHR chart, despite some affiliates (especially in some Asian countries) playing the "Twin" English version of the said song, while some US affiliated stations played the English-only version of the song without rap. The HAC chart, however, aired the "Twin" version. Similarly in July 2023, the HAC chart aired the acoustic version of Lovelytheband's "Sail Away" instead of the original (which was played by most affiliates).

In August 2023, AT40 played the no rap version of Jungkook's song "Seven" despite the rap version featuring Latto receiving airplay in most affiliates. However, the show went back to airing the version featuring Latto on the countdown on the September 2, 2023 edition. The same was done for Doechii's song "What It Is (Block Boy)" with the countdown playing the solo version, while some affiliates played the version featuring Kodak Black.

Disco and rap

As has been mentioned previously, many rock radio stations in the late 1970s adopted anti-disco stances, and this, too, was reflected in the way some affiliates edited AT40. For example, one 1979 show featured a story about disco saving New York; again, the show was structured so that anti-disco stations could edit the story out of the show. (Notably, Kasem ended the monologue with the prediction that "disco is here to stay," which was proven false in short order, as disco rapidly fell out of fashion by 1980.)

More famously, on the weekend of July 7–8, 1979, Cleveland, Ohio AT40 affiliate WGCL (now WNCX), instead of carrying AT40's "Top 40 Disco Songs" special because of being an anti-disco radio station, did its own version of American Top 40 using the July 7, 1979, Billboard chart as the source with Townsend Coleman handling the hosting duties for Casey Kasem. The special Cleveland-only American Top 40 episode did not feature the AT40 Archives, extras, or Long Distance Dedications – just the top 40 singles of that week, which was preceded by a recap of the previous week's top three. This version was also presented live on the air, unlike AT40, which was produced and recorded several days in advance. Because the station did not have disco songs in the playlist, and the top 40 that week had several disco songs, WGCL had to reach outside its library to find copies of some of the songs, some of which were not the single versions; "Hot Stuff" and "Bad Girls" by Donna Summer, the songs occupying the No. 3 and No. 2 spots on the Billboard chart for that week respectively, were conveniently available as a 12-inch medley, which Coleman used for the show. Through clever editing, Coleman also took the "Casey's Coast to Coast" jingle (pronounced "K-C's Coast to Coast") and spliced in a "T," to provide an appropriate "TC's Coast to Coast" jingle. Kasem himself did not learn about the deception until 1996, laughing the whole thing off by saying, "Maybe I don't want to hear it!"

Coleman's sleight-of-hand was actually the second time a version of the AT40 had aired that was not quite on the up and up. According to Rob Durkee's book "American Top 40: The Countdown of the Century", Dave Morgan of WDHF (now WCHI-FM) in Chicago ghosted an edition of the program sometime in the summer of 1975. When the station's copy of the show did not arrive in time, he used Billboard's list and merely played the records, apparently heavily implying that the show was American Top 40 without actually identifying it as such. "My program director made me do it!" Morgan said years later. The following year, WDHF would refuse to play AT40's "Fourth of July's Greatest Hits" special, because No. 1 hits from the pre-rock era were overabundant in the special. But while the special was a stark departure from the contemporary sound of the 1970s, Tom Rounds in his press release reminded stations that it was the United States' "one and only bicentennial."^[50]

From 1992 to 1994, two radio stations still carrying American Top 40 had to carry customized versions of the show. WPLJ in New York City aired the show with the urban/dance/rap songs mentioned but not played and were replaced here and there by Hot Adult Contemporary-leaning extras. KUBE in Seattle, Washington, aired AT40 with a few songs that did not fit the station's Top 40 Rhythm format omitted each week.

Annual Countdowns

The top songs of the year are counted down near the turning of each year, though the format has varied over the years.

• Top 40 (over 1 week): 1971, 1973, 1999, 2010–present*
• Top 50 (over 1 week): 1979, 1994
• Top 80 (over 2 weeks): 1970, 1972
• Top 100 (over 2 weeks): 1974–78, 1980–82, 1992, 1998, 2000–09
• Top 100 (over 1 week): 1983–91, 1993

During the show's original run, the 2-week Top 100 programs came with special instructions for editing the show into one 8-hour block. Conversely, the 1-week Top 100 programs came with instructions to split the show into two 4-hour blocks.

In 1971 and 1973, only the top 40 was counted down because of AT40's Top 40 Christmas Countdowns which aired the week prior. The show did not air Christmas countdowns again until the spinoff shows "American Top 20" and "American Top 10" came into existence, as both of these spinoffs aired a "Top 60 Christmas Songs" special annually the two weeks immediately preceding Christmas.

In 1994, the show was no longer airing in the US, and would be put on hiatus a month later.

Since 2010, the show has aired the same Top 40 year-end chart two weeks in a row, with the only differences being the optional AT40 Extras and re-cut announcements mentioning the Dick Clark's New Year's Rockin' Eve (which Seacrest also hosts) as a past event instead of an upcoming event. An exception to this was in 2019 when the year-end chart was aired only on the weekend before Christmas, because the decade-end chart would air the following weekend, with the normal chart resuming the first weekend of January.

Decade-End Countdowns

In 1979, 1999, 2009 and 2019, the show aired special countdowns of the decade's biggest hits. In 1979 and 1999, the annual year-end countdown show was cut to one week (4 hours) to accommodate the special countdown, though in 2009, they aired a third special week after their usual two-week Top 100. The decade-end shows counted down the Top 50 of the 1970s, and the Top 40s of the 1990s, 2000s, and 2010s. There was no decade-end countdown for the 1980s.

Guest hosts for Ryan Seacrest

Only Katy Perry, Joe Jonas, Jimmy Fallon, Andy Grammer, Sabrina Carpenter, Bazzi, Taylor Swift, Alessia Cara, Lauv, Ed Sheeran, Ava Max, Charlie Puth, and Pete Wentz filled in for Seacrest twice or multiple times (though Jonas did solo in 2011 and with DNCE in 2015). Only two artists had the number one song the same week as guest host and they are Shawn Mendes with "Stitches" and Gayle with "abcdefu".

Since 2021, there are also some artists who became guest co-hosts for some portions of the program (while Seacrest hosts the remaining parts), including:

• Ed Sheeran
• Silk Sonic (Bruno Mars and Anderson .Paak)
• Charlie Puth
• Tiësto and Ava Max^[55]
• Blackbear^[56]
• Lizzo^[57]
• Gayle

Only Ed Sheeran filled in for Seacrest on some portions of the program twice. Lizzo is the only artist in this list to hit number one when partially guest hosting when her hit "About Damn Time" went number one.

Guest hosts for Casey Kasem

Los Angeles deejay "Emperor" Bob Hudson attempted to substitute for Casey sometime between 1976 and 1978 (no specific date was given); however, Hudson had trouble recording his material for AT40, giving up after realizing that he could not host AT40 the same way he would host his morning drive show. As a result, Casey cancelled his vacation and returned to Los Angeles to record that week's AT40, but made sure that Hudson, a legendary disk jockey and comedian, got paid for his work anyway.^[59]

Guest hosts for Shadoe Stevens

¹ The week Jay Thomas hosted, October 31, 1992,^[60] Chris Cox of KEZY in Anaheim, California (now KFSH-FM) taped a special version for that station at Watermark's studios, because of contractual stipulations that prohibit talent from Los Angeles-based stations from being heard on KEZY (Thomas was still employed at rival KPWR at the time).^[61]