In the 70's I heard ZBM-FM 89.1 from Hamilton, Bermuda in Morton Grove, IL - 1,430 miles. That signal was staying in quite steady with a few deep fades for, say 10-15 seconds every few minutes for probably up to 10-15 minutes total as I recall then...who knows how long it was already coming in at my location when I started hearing ZBM ("Zed-B-M") ...I saw somewhere recently that ZBM-FM was operating at 15kW ERP though I have no idea what power they were using then in the mid-70's (roughly '76). Now only if I would fix the belt in my reel-to-reel recorder to play those FM DX tapes again!!!
It's fairly common knowledge that FM radio stations on islands usually don't have tall towers, since most of the time they are nearly at sea level and there is little to no terrain to interfere with signal reach, unless whatever island the station is on has mountainous terrain, then a tower or tower stub would be placed on a mountain...my understanding is that the height of the transmitting antenna is not very critical for Es to occur, but the beam width of the signal lobes would need to hit the ionosphere at a favorable angle obviously for the signal to bounce back down...I'm no propagation expert, for sure, just a theory... I have a 1971 World Radio TV Handbook, no TPO or ERP given for ZBM-FM. (this is the furthest east I have heard. Stateside, I have heard Philadelphia, Washington, Baltimore and Northern NJ WRSU 88.7 - Rutgers University, New Brunswick, NJ - but not New York City - why? Well, most of their channels are on the same frequencies as Chicago's metro area "Class B" signals are!)
Within the past 2 years I heard KVOD 88.1 Lakewood, CO 896 miles from Prairie Grove, IL (while driving in a rainstorm, they are at 1.2kW ERP (this is the furthest west I have heard) In the 70's I heard 97.3 and 101.5 from Miami also in Morton Grove, IL... approximately 1,202 miles. Heard KUT-FM 90.5 Austin, TX (1,225 miles), so that would be the most SW catch from the Crystal Lake, IL area.
Going north, WHSA Brule, WI - 339 miles (almost Duluth, but never Duluth...and I don't believe I have ever caught any Twin Cities stations...maybe KEEY 102.1...not sure)... at 339 miles WHSA would likely be Tropo...probably quite unlikely to be getting Single or Double Hop Es from the North "quadrant", say a bearing of 315° to 45° Since most of the Canadian high power stations are in the southern parts of Manitoba, Saskatchewan, Alberta, Ontario, British Columbia etc., that would be really tough to get single hop Es from way up north in Canada in Northern IL...