I have faint memories of the “S Curve” on LSD; mainly because I was very young when it still existed. I still think of it as the “Kick-S Curve,” which was how Steve Dahl used to refer to it on the air (and yes, I was probably too young to listen to the Stever back then).
Credit to DNAInfo for drawing attention to this pretty amazing reel from Chicago Film Archives. There’s a lot of iconic Chicago stuff to check out, including a great angle on the S Curve (about 2:00 in) which drives home why the curve needed to be updated in the first place.
It’s a silent movie, so maybe watch it with the Loop on in the background…