Just doing a little quick math....
My travels so far have taken me to 47 states. I did some quick math and calculate that I've heard a Chicago "1-A clear" in 42 of them (plus three Canadian provinces). At least 40...if not all 42...of the states, plus Manitoba, Ontario, and Quebec involve WLS.
The five states where I've been but haven't heard WLS or a Chicago clear would be Washington, Oregon, Utah, Arizona, and New Mexico. British Columbia would also be on my list. My guess is that with a determined effort, at least one Chicago signal would be do-able in each of these....even given today's crowded and noisy conditions.
I'll bet that the states you didn't hear WLS in were states you visited in more recent times, such as the last 20 years. In 1963 I heard all the Chicago clears in Oregon, Washington & British Columbia.
One specific & very memorable DX night for me was in Seattle in August 1963. I heard all the Chicago clears, plus lots of east coast stations.
That night I heard WNBC, WABC, & WCBS NYC, plus WCAU, WBZ, & WHAM all in Seattle on a Sunday night in August.
My only regret is I didn't have a tape recorder available.
Those conditions would've left me "sleepless in Seattle" fer sure!
And yes, most of my Chicago catches in the west were back when things were less crowded/noisy. Some of it, however, has to do with logistics and lack of a dedicated effort on my part. One place where I have made a few attempts at the Chicago big boys is Burlington, WA....a handy place to spend the night about midway between Seattle and Vancouver. Except for local pest KAPS on 660 a couple of miles up the road from my hotel, the location is a pretty good DX spot....relatively noise free.
And I don't recall the xylophone/vibraphone weather sounder or the ID on the WLS overnight show....although both vaguely ring a bell. (no pun intended!). In the late 60s, I'd have been in college in Iowa....where after midnight I'd probably have been either spending quality time with my girlfriend, DXing, or hanging out on the high end of the dial flipping between KOMA, WLAC, and XERF (if not sleeping). I didn't listen to WLS very much at night because we were in a convergence zone and it sounded awful.