"AM, and How! Not All Stations on the Senior Band Are Struggling"

"Arbitron ratings from some of the largest markets in the United
States reveal that some AM radio stations in the largest markets are
very highly rated. Financial data from BIA/Kelsey, a financial and
strategic advisory service, suggest that some are very profitable,
too.Similarly, the same can be said for some small- and medium-market
AMs, where local high school sports and agricultural news bring in a
lot of local ad dollars... WGN, which he said turned off its HD Radio
earlier this year because of concerns it was causing interference,
broadcasts the Chicago Cubs and Chicago Blackhawks, further
identifying with this sports crazy city, Langmyer said. We cume a
million listeners. This is an AM market if there ever was one. There
are a lot of great AM stations here and they drive a lot of people to
the AM dial."

http://www.radioworld.com/article/89902