That frequency is usually chosen in small AM radios because it is a fair compromise between 1 ) ease of constructing high-Q resonant transformers in the radio IF amplifier; 2 ) high enough for acceptable image frequency rejection by the radio front-end tuned amplifier; 3 ) by being a " de-facto " standard there should be no strong transmissions at 455 kHz and components are standardised e . g . fixed-frequency ceramic filters are now often used instead of wound coils.
