> But in Taiwan. Most emergency radio and music radio including illegal radio sites are in FM instead of AM. Taiwan is tiny. You need only a few FM towers to c

> But in Taiwan. Most emergency radio and music radio including illegal radio sites are in FM instead of AM. Taiwan is tiny. You need only a few FM towers to cover the whole country. FM's range is low. AM's range is much, much higher: "However, during nighttime hours the AM signals can travel over hundreds of miles by reflection from the ionosphere, a phenomenon called "skywave" propagation. (Shortwave stations, which operate using AM modulation on several bands between between 2.3 MHz and 26.1 MHz, also use this phenomenon to broadcast still greater distances, up to thousands of miles.) Because of this change in signal propagation from daytime to nighttime, if every AM station kept its daytime operating power at night, massive interference would result. (For a similar description, see Hours of Daytime-Only AM Broadcast Stations, First Report and Order, BC Docket 82-538, 95 FCC 2d 1032 (1983) [ PDF ] and related [ MO&O ])." https://www.fcc.gov/media/radio/am-stations-at-night https://www.fcc.gov/media/radio/am-stations-at-night In the US, it's used for all kinds of stations - mostly junk talk shows and sports. And yes, emergencies. When driving on highways, you'll often see signs with lights telling you to tune into a certain AM frequency if the lights are flashing (e.g. landslide ahead).