Former call letters were WCLR. WCLR surfaced on the 101.9 frequency in the late 1960s. The station ran a "beautiful music" easy listening format for years. The station played easy listening renditions of pop standards/other songs along with a few easy listening vocalists and AC artists. The station dropped the instrumentals in the late 1970s and became a very Soft AC station still known as MOR playing a blend of easy listening vocals and softer AC songs from the '50s to '70s.
By the early 1980s, the station evolved to a straight-ahead AC format with studios located at 8833 Gross Point Road in Skokie, Illinois. WCLR was "Chicago's Lite Rock" from about 1982 until 1989. The station was best known for its soft rock and lite rock starsets in the 1980s and their Saturday night all-request oldies program.
In 1990, WCLR moved to a hot AC format, changed its call letters to WTMX, and became known as "The Mix". By 1995, WTMX had moved its studios to the Prudential Building in downtown Chicago and began leaning more toward modern rock. By 1996, the format was modern AC, basically modern rock without any hard rock. They played more female vocalists and '80s retro music than most modern rock stations and were hot AC in tempo and presentation.
In September 1996, The Mix debuted the Eric & Kathy morning show fronted by Chicago natives Eric Ferguson and Kathy Hart. They have listenership among advertiser-coveted 25-to-54-year-old females for most of the 10 years they've been at the station. The key to the success of this entertainment based, lifestyle driven show has been its ability to keep the content edgy enough to engage grownups but clean enough to sail right over the heads of youngsters. On any given week The Eric & Kathy Show will feature interviews with top Hollywood celebrities, including Reese Witherspoon, Oprah, Vince Vaughn, Matthew McConaughey and others. In addition to celebrated guests, the show has played host to live performances from platinum selling, chart topping artists like Goo Goo Dolls, P!nk, Dave Matthews, Bon Jovi, John Mayer, Lenny Kravitz and others.
In February 2006, WTMX began broadcasting in HD Radio. WTMX's HD-2 format features music from independent, unsigned bands called "iChannel". Both streams are broadcast on the web along with an all 80's channel called "Totally 80s"
Also in 2006, WTMX evolved toward an adult top 40 format with the addition of pop-crossover music by artists such as Rihanna, Justin Timberlake and Timbaland, while still retaining many of the modern AC artists they have been playing since 1996.
Current roster includes: Eric Ferguson, Kathy Hart and Melissa McGurren (mornings), Koz (afternoons), Jeff Corder (evenings), Mike Roberts (overnight)