That wasn’t (isn’t?) uncommon, it had to do with the different propagation at night that @David_Guilbeaul mentioned above. It probably meant that the Boston station had the same frequency as some 24-hour powerhouse transmitter farther away (& who had their broadcast license first, or deeper pockets, or both, though it might’ve also had to do with which station was higher up the EBS chain).
In the DFW area (40+ years ago) the old TV listings in the Sunday paper also had a list of area radio stations and at least a few of those were sunrise-sunset. Another was the powerhouse WBAP mentioned upthread; I believe that transmitter was a few miles south of us and, for several years, its flashing white strobes were the only thing we’d see in that direction at night - the rest of the area was just dry prairie back then. Speaking of WBAP, my dad & I built a crystal set from Radio Shack (spring terminals; no soldering required) and the only station it would reliably pick up was WBAP (which at the time played “Cow Patti” a lot)
There was an AM station that played jazz (at this far remove I remember it being bebop or hard bop, like Jazz Messengers). I think it was one of the sunset-sunrise stations. I had an AM radio (again, Radio Shack) that fit on my bike handles and that jazz station came in pretty well. My friends & I dug it & would pantomime along with what we were hearing, but I never listened long enough to hear them announce who/what they’d played. I don’t think that station lasted long after that, or I might’ve gotten into The Music that much sooner.
Anyway… as far as emergency alerts go, there are hand-cranked/chargeable flashlights with built-in radio (incl. AM & WX), though now I don’t know where mine went so, dang, maybe I do need a car radio for emergencies…
ETA: in the mid-1990s Austin got an AM station that played what I guess those in the industry would call Urban Oldies - anything from The Platters to Parliament (though once they went back as far as Erskine Hawkins). After a few years it was less and less of the oldies, but one morning (in 2000 or so) it had changed completely to a “men’s talk” format which was misogynistic garbage.
(ETA for typoe’s)
