"I live in a semi-rural area and all but the most powerful nearby AM stations (Absolute Radio, 5 Live, and Talksport) are basically unlistenable because of the local noise. Can't imagine how bad it is in a city!"

Yes, you're right. I don't have to imagine, I know.

There are two problems here although many will disagree. The first is that AM radio is on its last legs and it should not be so. As I grew up with AM radio some would say it's just nostalgia (and you cannot build a crystal set radio for digital radio). Partially true, but it's irrelevant. I'd argue that AM radio - like the point I made in my second post about NATO's HF fallback strategy - is of strategic importance. First, because both its transmitting and receiving technology are simple and can be cobbled together with minimum resources and cost. Thus, in emergencies, natural disasters, nuclear war or even a backup when fiber optic cables or satellite comms fail, it serves a useful purpose.

The key advantage of AM broadcasting is that its service area range is much larger than say FM broadcasting - especially so its secondary (and even its tertiary service) areas - even in daytime when ionospheric skip is absent. Of course, at night time when the skip kicks in that distance is
extended substantially - that is if there is no interference.

Let me give you an example. I'm in Australia and years ago I could drive from Sydney to Adelaide some 840 miles and listen to the national broadcaster the Australian Broadcasting Commission (ABC) - sort of equivalent to NPR - all the way without interruption or significant interference except for switching frequencies, three in total.

The three transmitters were located in Sydney, Melbourne an Adelaide and Melbourne was not on the way but hundreds of miles tangential to the cross country route. Moreover, this was daytime reception without the aid of ionospheric skip. There is absolutely no way this could be accomplished with 88-108 MHz FM transmiiers, it would take many dozens of them to service the route (and even now it's sparsely populated - mainly hundreds of miles of semi arid desert, thus there's no way one could justify the cost of FM coverage).

Unfortunately, nowadays that is no longer possible due to the increased noise floor within the AM band and the fact that more adjacent and co-channel services have been added.

AM broadcasting is especially useful (or it ought be) in rural or sparsely populated areas especially in large countries such as the US, Australia, Canada, Russia, etc. It's madness to close these services down - and it's also the reason why we need to protect such services from increasing noise and interference.

BTW, I say this as a person (one of a half dozen or more) who was instrumental in getting FM broadcasting services established here. No, I'm not a traitor to the FM cause. What I'm saying just makes strategic and pragmatic sense - it's a shame governments have lost the plot on this. It'll likely be too late when the need arises and all services have been shut down.

A final point, I've always believed that AM radio is one of the greatest and most significant engineering developments of the 20th Century. After the telegraph, it was the next 'quantum' leap in communications and an essential stepping stone to latter services - FM and TV broadcasting, satellite communications - even the internet. Unfortunately, its gloss has rubbed off and it no longer gets the recognition it deserves.