Prior call letters for 97.9 FM in Chicago were WVON-FM, which stood for "Voice of the Negro," in reference to its original African-American audience, and WSDM-FM.
Owned by the Chess family of Chess, Checker and Cadet Records fame, through their company, L & P Broadcasting. "L" stood for Leonard Chess, who primarily ran the Chess record labels and recording studio, while brother Phil Chess ("P") was president of the radio company. Son Terry Chess was General Manager of WSDM through much of the early and mid-70's. The WSDM call letters acronym stood for "Smack Dab in the Middle", "the middle" meaning the exact middle of the FM radio dial. The radio station positioned itself as "jazzed up rock" and the "station with the girls" — a reference to the all-female air talent. Its original program director was Burt Burdeen. Among the disc jockeys were Connie Szerszen, Cindy Morgan (who later left radio, went to Los Angeles and became an actress, her career including roles as Chevy Chase's girlfriend in "Caddyshack", and a lead role in the sci-fi film, "Tron"), Danae Alexander, Linda Ellerbee, Yvonne Daniels, Kitty Loewy and Gloria June. There were guys on "the station with the girls", too. Announcers such as David Witz (cousin of former WCFL General Manager Lew Witz) and Don Davis (later an air talent on WDAI/Chicago and then a Program Director for DC-101 in Washington, DC and WCKG-FM in Chicago) appeared on WSDM in the mid-70s. Davis made the transition from WSDM to the WLUP airstaff when the format changed in 1977.
Congressman Cecil Heftel (from Hawaii) purchased the radio station in early 1979, kept the call letters and "Loop" identifier. Lee Abrams was hired as consultant. The rock format was kept in place, but emphasis was put on harder-edged rock. Steve Dahl, who had been unemployed since WDAI (94.7) went to a disco format in December 1978, becoming the basis for the most imfamous promotion in Chicago sports history, Disco Demolition Night, was hired for mornings in March 1979. Overnight disc jockey Matthew "Mondo" Meier was teamed with Dahl to do news. He started using his real first name "Garry." Garry became Steve's full-time sidekick when Buzz Kilman was hired as the newsman in 1980. Chuck Swirsky provided sports reports. Steve and Garry were fired in 1981 for "assaulting community standards". A series of morning men including Matt Bisbee and Mark McEwen tried their hand until Jonathan Brandmeier was hired in 1983. Kilman remained as newsman and Bruce Wolf replaced Swirsky when he went to WGN in 1981. Steve and Garry returned in 1986 to host afternoons.
In 1985 Heftel Broadcasting bought AM 1000 WCFL, which was a Christian music and teaching station. In April of 1987 that station became WLUP "The Loop" as well as making the FM station WLUP FM. The religious format was dropped from 1000 WLUP and the station simulcast WLUP FM overnights. During the day though WLUP 1000 ran a full service rock format while focusing on talk. By 1990 the AM station would evolve to mostly talk with a few rock songs mixed in an hour.
WLUP FM also began mixing more talk into the format by simulcasting the AM station and evolved to a Talk/Comedy format by 1993. Shortly after, the AM station became a sports station. WLUP FM became WLUP again and evolved to a talk format with a few rock songs mixed in per day.
In the early 1990s, WLUP aired a popular television commercial featuring a fat man dubbed "Joey Bag O' Donuts" dancing to Aerosmith's "Walk This Way".
WLUP (97.9 FM) in Chicago was one of the first stations to have the "FM talk", comedy talk format in the early 1990s. Some of the shows were Steve Dahl and Garry Meier, Danny Bonaduce, Liz Wilde, Kevin Matthews, Jonathon Brandmeier, with News man Blues man Buzz Killman, Chicago Ed Schwartz and Seka.
By the early 1990s, Heftel had acquired a lot of Spanish radio stations. Its English speaking stations were sold off one by one, and WLUP FM was sold to Evergreen as a result. Evergreen kept the talk/comedy/rock format. WLUP switched to a modern rock/Hot AC format late in 1996. In 1997 Evergreen and Chancellor merged. Evergreen opted to sell WLUP to Bonneville in July which already had a modern rock/Hot AC outlet, and they then switched WLUP to a classic rock format. Brandmeier left WLUP and Kilman became the morning man for a brief period before he rejoined Johnny B. at WCKG. In June 1998 WLUP adopted the slogan, "Classic rock that really rocks".
In 2004, Emmis Communications traded three of their stations in Phoenix to Bonneville for WLUP-FM and $70 million. One year later, Emmis brought back Jonathon Brandmeier to do mornings on The Loop again.
On January 15, 2007, Chicago's NBC affiliate, WMAQ-TV channel 5, began a new weekday morning show called Barely Today'' which airs from 4:30-5 a.m. The new morning show is simulcasted on WLUP-FM and is hosted by Bruce Wolf, who was the former weekday morning traffic/sports anchor for WMAQ.
On April 25, 2008, The Loop crowned it's first ever Rock Girl Roadie winner, Mike Gentile, a paramedic, from Westchester, Ilinois, at the Loop Rock Girl Finals at Austin's Saloon in Libertyville. Gentile gets to shadow the station's spokesmodel, Kelly, also known as The Loop Rock Girl, for an entire year as she goes onstage for band introductions, backstage to meet musicians or in the front row of the audience to watch the show. Gentile keeps a detailed blog for The Loop's Web site about all of his experiences. Gentile has recently gained local celebrity status when he hosted a Hometown Tour pilot with 97.9 "The Loop's" Mid-day radio personality Erin Carman and with a highly viewed video featuring the 2008 Loop Rock Girl, Kelly, getting guitar lessons from Mike. In the video, Kelly hint's that there will be a series of video's showing her progression.
On 2008-09-08, Emmis announced a programming partnership with WorldBand Media and will be using WLUP's HD-3 signal to produce programming for the South Asian communities in 3 major cities including Chicago. The said content will be available in Mid-October.
Weekend and sub DJs include Pete McMurray (Saturday Mornings), Tom O'Toole (the first WLUP DJ to sign on), Jill Egan, Mike Noonan, Pat Capone, Alan Daley, Don Nelson, and Christine Moran.
Some of the theme shows include:
The weeknight shows are hosted by Byrd. He also does "The 11 O'Clock Shocker" when he hand-picks a song that is rarely played in the station's music programming.
"Saturday Night Rock of the 80's" is hosted by Pat Capone.