In response to my above post, San Francisco is still one of the few markets where they still make mention of the AM signal. FM coverage in that market by default is terrible. Most every station has multiple boosters.

Several FM music stations (99.7 KFRC, 96.5 KOIT, etc) had AM sister stations simulcasting the music format for the same reason (Bad FM coverage) well into the 2000s. KFRC-FM (99.7) simulcast with the legacy KFRC-AM (610) until the swap with Family Radio. I believe 96.5 KOIT was simulcast on 1260 until the Mid-Late 2000s.