John: This crude map is courtesy of Radio-Locator.

I have always believed AM stations have problems penetrating buildings while FM stations can easily do so.

For those working in office buildings back in the day, how did they listen to music stations on AM? The radios were cheaper back then. I've heard GE, yes, the maker of light bulbs to jet engines, made a super-radio which could receive nearly anything.

Speaking of Chicago radio reception; is a tall antenna height for an FM station superior to a shorter antenna with more watts pumping through the transmitter?

Look at Los Angeles. Many of those stations are grandfathered in. When I was in Los Angeles the last time, I could hear KLOS-FM 95.5 nearly one hundred miles from their transmitter atop Mount Wilson in L.A. Their ERP is 61,000 watts with 3,130 feet above average terrain. Height above sea level is 6,073 feet. I'm surprised those who live close by don't hear KLOS-FM in their teeth fillings.