I remember the WLS/WCFL battle from summer vacation (Honor, MI) in 1975. Honor actually skipped the radio age until the FM era, before FM, they waited until sunset to listen to the radio. WCFL's evening DJ was making fun of an awful song called "Run, Joey, Run".
When we came back for 1976, we found that WCFL had flipped to beautiful music (is it just me, or was beautiful an awful choice for a 50kW AM by 1976? Had the last FM with the format in Chi given up by then?) WLS was still T40 and had a strong signal, with the other strong music signal being WOWO (my older brother preferred WLS while I preferred WOWO, which leaned a little toward AC).
I was listening to some country music in that era as well, and living on the far east side of Detroit proper, Class IV WEXL and 1500 WDEE (which, at the time, probably had the tightest directional pattern in all radio - 12 towers, and in one tight lobe, unlike KLIF's) both got a lot of interference at night, so WSM actually had the best country signal at night (CKLW-FM was country, but the only FM radio in the house could not take earphones).
Anyway - back on topic - 1520.
In Detroit it was a very weak WYFC by day (WYFC was a tiny religious daytimer that moved to 990 years later), and nothing but WLAC and WCKY slop at night (no sign of KOMA nor WKBW, though I did once catch WKBW around sunrise).
In Temperance, I had picked up KOMA, WKBW, Muskegon and Sikeston, MO, none ever really listenable.
By day, it had been a station with 12 towers sprawled out over about 15 miles (!), with six of the towers just south of Temperance (less than half a mile north of the Ohio state line, a/k/a the Toledo city limits) for daytime broadcasting beaming south, and the other six south of Toledo, beaming north. The station has had many call letters, currently WNWT, but probably best remembered as WVOI. They later stopped using their Ohio night array, continuing to broadcast, but as a daytimer from the Michigan site/studio. In later years, only their audio ended at sunset - they continued to transmit a dead carrier from the daytime site all night.
About 10 years ago, they replaced both of those arrays with a single new five tower array a little further south of the old night array. Though their power actually dropped from 1kW to 500d/400n, the new array really gets out! I have not logged a new catch on 1520 from here since the new array came on. WSPD is the only Toledo AM that covers the market better than 1520 - and not much better at that (ironically, the best AM coverage of the Toledo area is from Detroit-COLed WJR, with CKLW and now - since an upgrade - CFCO in Chatham arguably covering the greater Toledo area better than WSPD).