I know the broadcast flavor of the year is to move news + talk stations to FM. Before pulling the trigger CC will most likely take into account WBBM AM with the FM signal has not really pushed them ahead. Places where the AM signal was marginal Atlanta* + DC, FM has worked wonders. 840 AM is not "signal impaired".
* All North GA AM's suffer with very poor soil conductivity.
As soon as your radio gets near any part 15 monster 840 is impaired. It's just the nature of the beast.