730 kHz 

The AM frequency of 730 kilohertz is defined by the FCC as a  Class A, B, or D  frequency.    In Idaho, KBSU is the only station on 730.  Across the US, however, there are over 30  stations assigned to this frequency, several in Canada, and several in Mexico and other North American areas.  It is for this reason stations on this frequency either reduce power or switch to a directional antenna (or both) at night to reduce interference.       (Information updated Feb 2008)