Wow Dixie, that totally rocked! 
I'll bet you think the Bay City Rollers were total rockers too. 
Maybe musical taste is different in the South, but I never hear Chicago on the classic rock stations here. I don’t think I’ve heard that tune you posted in like 15 years.  Classic rock, in the non-retarded sense of the word is Zep, Floyd, Stones, Neil Young, Tom Petty,  AC/DC with some 80s and 90s rock tossed in for good measure.   My distinct impression is that if Chicago is played at all, it’s on those easy-listening oldies stations.  The ones no one under the age of seventy five ever listens too. 
question:  Why did a lot of those seventies “rockers” like Chicago and Styx sing like they took mass injections of estrogen?  What’s up with all the falsetto harmonies and soprano vocals?  I think Joan Jett or Chrissie Hynde  could teach those fancy boys how to sing an actual rock tune.