Gimbels Department Store expanded into the radio business in 1922, signing on WIP, Philadelphia’s first radio station.
WIP was a Mutual Broadcasting System affiliate during radio’s golden era in the 1940s and 1950s. it signed on an FM simulcast in 1942.
Metropolitan Broadcasting, a division of Metromedia, purchased WIP-AM-FM in 1960. After an attempt at a Top 40 format, WIP went after 25- to 49-year-old listeners. it adopted a middle-of-the-road sound, featuring some adult pop music and extensive news service.
WIP-AM added more soft rock to its playlist, evolving into a full-service adult contemporary format in the 1970s, featuring strong personalities and robust local news. WIP was the city’s top-rated station in that era.
As FM began to erode the audience for music on AM, WIP added more talk programming in the 1980s. It moved to all-sports by 1988.
In 2011, owner CBS Radio flipped rock station WYSP-FM to a simulcast of WIP-AM’s all-sports format. The simulcast gradually split over 2011 and 2012. WIP-AM became a full-time affiliate of CBS Sports Radio in 2013, airing national programming as WIP-FM aired local sports programming.
As of 2014, CBS Radio owns WIP-AM-FM.
The original WIP-FM became WMMR in the mid-1960s, airing a MOR format separate from WIP-AM. In 1968, it flipped to a progressive rock format. It has carried a rock format ever since, becoming one of the nation’s premier rock stations. As of 2014, Greater Media owns WMMR.
Sources: Wikipedia (WIP-AM), (WMMR-FM), Philadelphia Radio Archives (History of WIP)