Yep, that was a thing with NTSC-M analog channel 6, which had the audio at 87.75MHz, just below the nominal bottom of the FM range at 88.1MHz. I used to listen to the 10 o'clock news that way.
ISTR we had 2,4,5,9,11, and 30 (UHF). Channels 2-5 were ABC, CBS, and NBC. Channel 9 was PBS, and 11 and 30 were local stations that weren't affiliated with any of the major networks.
2, 4, 6, 8, 10, 13, and UHF 30.
I also remember that depending on the radio, you could sometimes pick up the audio for I think VHF channel 6 at the low end of the FM dial.