Why do am radio stations cut there broadcast power at night?

Answer 1

50,000 Watt stations don't cut their power. Such as KKOB, KFAB, and others.

some 30,000 Watt stations, such as KSL, don't cut their power, and some do.

10,000 Watt stations, such as WKRP, cut their power, simply because AM goes farther at night.

Example: In the daytime, KKOB covers most of NM, while at night, it covers the entirety of the Western half of the United States. Try it sometime. At like 11:00 at night, tune in to 770, and you will hear Coast-to-coas AM, literally covering coast-to-coast perfectly or close-to-perfectly from ABQ, NM.

Simple. You have a radio station right next door to you, (like a mile away) and you can't hear it because the station from farawayville is bleeding in massively, Ex: there is a 1600 AM station in NM, but one in Washington, too. At night, they will bleed into each other, making each other obsolete.

Without doing this, at night, AM will be a bunch of heebajeeb.