Decades ago, a Chicago radio geek told me how in downtown Chicago, the steel - cement sucked up/sucked in the AM signal. He said it was horrid.

Too, I've read on KNX vs KNX-FM. The mountains come into play out there (Los Angeles) and there are those who say the AM is better.

There's talk of that here, though I cannot find the exact thread, if it was even at this site:
https://www.radiodiscussions.com/threads/knx-los-angeles-website-shows-97-1-and-not-1070.743837/

"The AM already suffers from existing electric sources interfering with the signal as a result of increased urbanization. Plus, electric cars have ditched AM due to the presence of static from components."

https://radio-locator.com/cgi-bin/pat?call=KNX&service=AM

https://radio-locator.com/cgi-bin/pat?call=KNX&service=FM