630 kHz 

The AM frequency of 630 kilohertz is defined by the FCC as a Regional Channel Class B or D frequency.  In Idaho, KFXD is the only station on 630.  Across the US, however, there are over 20 stations assigned to this frequency, several in Canada, and over 30 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 Jan 2008)