NorthPine: Upper Midwest Broadcasting

Living History: Long-Distance Signals from ‘Golden Age of Radio’ Still On Air

A family is seen listening to the radio in the 1934 AT&T short film "Network Broadcasting."

When people talk about long-distance AM reception, it’s often discussed as something that happened in the past.

Those skywave signals from the “Golden Age of Radio” are actually still on the air. The longer nights of fall and winter provide more opportunity to hear them, though instead of Jack Benny or Dragnet, the old “clear channel” stations are mostly now carrying talk, sports, or news.

People who did not grow up with AM radio are usually shocked the first time they hear a distant AM station. When I first heard Chicago’s WBBM in the Twin Cities as a teenager, I thought it must be a rare catch. Then I tuned in again and again and realized it happens every night.

While internet streaming and syndication have taken a lot of the excitement out of listening to scratchy out-of-town signals, it’s still interesting to observe the phenomenon that is AM skywave reception. The skywave signals are also a nice companion when you’re at a remote northern campsite or on a long drive through a rural area.

The reason AM signals travel so far is that the atmosphere treats mediumwave (AM) wavelengths differently depending on whether the sun is shining. During the day, the signals are absorbed by the atmosphere.* At night, they bounce back down to earth in a way that’s so predictable that AM stations have to factor in stations hundreds of miles away when building or modifying transmission plants.

In the very early days of radio, the industry and regulators recognized the potential of massive signals to serve rural areas that had few or no local stations. They reserved certain frequencies for 50,000-Watt stations that cover part or all of the continent at night.

These stations are still on the air, mostly with the same coverage areas they had back in the 1930’s (here’s a look at the stations commonly heard in the Upper Midwest). However, they do fade in and out and the signal strength varies from night to night.

The AM band is divided up into three types of frequencies:

In recent years, there has been a lot of talk about further reducing protections for the former clear channels since there are virtually no populated rural areas without local radio service. However, legislators can’t change the laws of physics, so skywave signals will still exist even if they’re no longer protected.

But it may be the laws of economics that ultimately end skywave reception. It’s no secret that AM listenership has been declining for decades, and there has been a trend of owners downgrading smaller AM stations or taking them off the air completely as their transmitter facilities age.

So, experience those skywave signals while you can.


More information:

*This article has been corrected to note that daytime signals are absorbed by the atmosphere rather than going out into space.

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