The FCC's latest quarterly station count indicates that the number of
commercial AM stations on the air slid from 4,803 at the end of Q3 2003 to
4,770 at the end of Q3 2004. This continues a trend that has been seen by
the senior broadcast band all year. At the same time, the FCC counts 6,217
FM stations on the air at the end of Q3. That's 10 more than last year.
Including noncommercial FMs, there were a total of 13,450 radio stations on
the air at the end of Q3.

Their space will be taken up by IBOC sidebands.

(Brock Whaley, DX Listening Digest)