Through the dark days of the Oldies format in the mid-’00s, most fans would have been happy to have just one FM station fill a hole that many radio observers expected to remain vacant forever. Now, in final confirmation of the resurgent appeal of the revamped Greatest Hits format, the battles have started to pop up, in markets from Las Vegas to Edmonton, Alberta, from Albany, N.Y., to Chattanooga, Tenn., and now in Chicago where CBS has flipped WJMK (Jack-FM) to K-Hits 104.3.

It’s not hard to parse CBS’s decision. Classic Rock, where the Chicago Jack was living most recently, was crowded; (ironically, however, WLUP had recently moved away from Jack’s ’80s variant to a more traditional Classic Rock format). CBS dominates the Oldies/Greatest Hits format in the top 10 markets. WLS-FM, with Scott Shannon’s “True Oldies Channel” in middays and overnights, is the sort of quirky-by-choice station that rival operators like to take a swing at, although it’s not that far to the left of WCBS-FM New York. And it’s now in the midst of the Citadel/Cumulus merger.

The last Oldies battles were during the format’s FM explosion in the late ’80s/early ’90s when the rules about how to do Oldies were still emerging. Initially, the game plan for an insurgent was usually to be tighter and more like the ultra-conservative KRTH (K-Earth 101) Los Angeles than the next guy, and often with the same neo-Bill Drake-era presentation as K-Earth. Then, some new Oldies FMs tried to get attention by playing more of the late ’50s and early ’60s than the incumbent—the formula that helped launch WBIG Washington, D.C., among others. Eventually, the various other format booms of the early ’90s—Country, the “Arrow” Classic Hits format—gave the second Oldies station a way out of the war of attrition.

In our small list of battles so far, the attacks have come from both sides and from operators of all stripes and sizes. KDOX (Kool 102.3) Las Vegas is an AM-translator combo doing an older-skewing version of the format as it might have existed on FM a decade or more ago. Albany’s WPTR-FM (Legends 96.7) also leans older. Edmonton is newer, with a music mix that goes after both Greatest Hits CKRA (Capital 96.3)* and the Bob- and Jack-like CKNG (Joe FM). And so far, you can also divide the battles between those stations that seem like they’re out to win and those that are just determined to take the other guy down a few pegs.

Having even one Oldies/Greatest Hits station in a market was helped greatly by the advent of PPM. WOGL Philadelphia was the first success story, but WLS-FM definitely got the industry’s attention with boxcar numbers on a format that some might have thought would be more of a niche. (WLS-FM has since tapered off in PPM, but so have some of the more typically programmed outfits, and it did have a strong January.) Part of the reason that PPM has been kind to the Greatest Hits format so far has often been the lack of competition, compared to the logjams popping up on CHR, another “PPM friendly” format.