Thanks, Scott. Do you have the Price/Whitburn type WLS and WCFL books? I think you'll find the 60s chart runs much shorter, as they were on the Hot 100. I seem to remember that the CKLW and WKNR charts from the 1960s topped out at about 13 week chart runs. The difference may be that they just dropped them from the ranked chart, and put them in a recurrent chart with much less airplay. It looks like WLS's charts were thoroughly researched, as evidenced by YLUML bouncing around in the 30s at the end of its chart run, before falling off. Mike Curb's Warner/Curb subsidiary had two other respectively lengthy runs, 24 weeks each for "December, 1963", and "Kiss You All Over". WLS and WCFL were extremely slow at adding Warner/Curb's "Who Loves You" and WLS was slow on the draw to add "December, 1963", and I think John Landecker made a crack about a sixties groups making the WLS survey, something like, "What is this, 1966?". And of course JRL played YLUML one night in 30 second intervals because he disliked it. Harder rockers seemed to begin take over the music selection on the WLS charts when they no longer had WCFL to kick around anymore.
In case you didn't hear the recent JRL interview on WWTN Nashville, this repeats the link from another thread.
http://wwtn.streamon.fm/listen-pl-41?smc=16&fbclid=IwAR0D1KYvUHFQt2ur__K-MTpHpX2PyIl_OkcGU2h5y1wmZqQToA02CZ_QrVw