1968–1979: Early years The station signed on the air on September 20, 1968. The original call sign was KACO, and it was owned by the Apollo Broadcasting Company. It aired an
adult contemporary (AC) and
middle of the road (MOR) format. A fire at the transmitter took the station off the air in January 1970. Two months later, the station returned to the air, changed its call letters to KGRV, and relaunched as "Music for Groovy Adults," offering a more upbeat AC format. This lasted until 1972, when it once again changed call letters, this time to KKSS, and rebranded as "Kiss 108". By 1974, KKSS switched to
country music. A year later, KKSS flipped to an
R&B format, dubbed "Black in Stereo". In February 1979, KKSS altered its R&B format and adopted the moniker "Studio 108," with a hybrid
disco music and R&B format, competing with WZEN (now
KATZ-FM).
1979–1997: CHUrban/UC In June 1979, the call sign was changed to KMJM and rebranded as
"The New Majic 108 FM, Where the Music is the Majic!". KMJM Was catered to both African-American and Caucasian-American listeners as the St. Louis
market's first "CHUrban" station (a forerunner to the
Rhythmic Contemporary format). At the time, the station was owned by Keymarket Communications. KMJM was ranked among the top five stations in the St. Louis
Arbitron ratings during the 1980's, as it shifted towards a mainstream
UC direction. In May 1988, KMJM was sold to Noble Communications of
San Diego for $19 million. KMJM's FM signal was one of the best in the St. Louis area, as the station emerged as the top urban station in the market.
Jacor bought the station in 1997.
1997–present: Top 40 On October 20, 1997, at midnight, after 18 years on 107.7 FM, KMJM was moved to recently purchased sister station
WCBW (104.9 FM), which aired a
Christian music format. After a 12-hour
stunt with a looped heartbeat and announcements redirecting KMJM listeners to the new frequency and the launch of a new format on 107.7 later that day, KSLZ and its current top 40/CHR format, branded as "Z107-7", debuted. The flip was to fill a format hole left by
WKBQ, who dropped the format for
modern AC on January 24 of that year. The final song on "Majic" was "Good Girls" by
Joe, while the first song on "Z" was "
Get Ready For This" by
2 Unlimited.
Morning shows At first, KSLZ was the St. Louis affiliate for the
MJ Morning Show, based at
Tampa sister station
WFLZ, and the only affiliate for the show outside of the Eastern Time Zone. After the show ended in February 2012, KSLZ became the St. Louis affiliate for
The Bobby Bones Show. After Bones relaunched his show to air on
country stations in February 2013, KSLZ replaced him with
Elvis Duran and the Morning Show. In December 2017, KSLZ dropped Duran for local host Jordan DeSocio. As part of company-wide layoffs, DeSocio exited the station in November 2020, and was replaced by "The Jubal Show", based at
Seattle sister station
KBKS. ==HD Radio==