Okay, Judge Carlyle stepping in here. As owner/operator of an AM STATION, and one in STEREO, I am uniquely qualified for this one.
AM is doing FINE when not shoved aside by large corporate interests. It's alive and well in many towns, making many people a living. It's the topic of a huge plan at the FCC called "AM revitalization, docket number 13-249 which you should all be reading and digesting, and asking question-of if you want to go wild on a topic like this.....and AM ain't going nowhere.
Now, to the technical: YES, cquam is available. Many transmitters have it. There's a major player in the AM antenna design field who will be bringing to market wideband stereo receivers within a year or less if their plan goes well, and YES, it sounds better. You get an (averaged) 10khz bandwidth on any AM station properly widened to it's NRSC allowance for occupation of the band. Add stereo, and you're TWICE the analog product leftover when AM IBOC is running, and on IBOC stations, the compression of the remaining AM and many receivers' inability to bounce between analog and HYBRID DIGITAL (it is not "HD" as in television, by the way, it's HYBRID DIGITAL) causes issues. So yes, continue cheering for AM, and for Cquam, it's always an option, and probably on it's way back...slowly but surely. Most corporate AMs have pulled the plug on HD-AM.
PROGRAMMING drives all audio media. Make the content good, people follow: AM, FM, podcasting, streaming, whatever.
I get damn sick of the insults to AM from those who are not working in it. People still buy CD's, even albums, and every media that has come out to compete in a different format has heard the naysayers proclaim, "(AM) Radio is dying. It hasn't and it isn't, nor will it be auctioned-off by the FCC for their money making machine, because it's at it's "highest and best use" now!
Unplug your noisy switching adapters and CFL's that make interference in your home, buy a radio that's NOT from WalMart, (spend a little....you get what you pay for....)..... doesn't say COBY or another cheap-donkey make, and start tuning the band. There's some pretty cool stuff out there. We are indeed, "wildly popular" with people who have local owners and program directors who care.
Oh, and for GREAT sounding AM, even at night, try the WION live stream. Info is on the thread dedicated to our station on Satguys. We send you REAL AM STEREO 24/7 from a tuner on the desk in my office.
Over and out.