690 kHz 

The AM frequency of 690 kilohertz is defined by the FCC as a  Class A, B, or D  frequency.    In Idaho, KBLI is the only station on 690.  Across the US, however, there are over 20  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)