We cant interrupt this (remote) broadcast. (Commentary).

THE 1996 Telecommunications Act relaxed rules limiting ownership in the radio industry, leading to fewer and fewer companies owning more and more stations. On June 2, the Federal Communications Commission will almost certainly grant a similar break for the U.S. television industry.

Which is why radio romantics -- those of us who lament the decline of American radio -- love to tell the following story.

In the early morning of Jan. 18, 2002, a train derailment near Minot, N.D. sent a poisonous cloud through much of the town. Immediately, police tried to broadcast emergency instructions to the community via one of the local radio stations.

Thanks to the 1996 deregulation, all six of Minot's stations are owned by Clear Channel Communications Inc. And on Jan. 18 -- in keeping with common practice at large radio companies -- the stations were broadcasting programming fed by satellite from San Antonio-based Clear Channel.

Which meant there was no one to answer the phone at any of the stations -- or to break into programming to broadcast news of the emergency.

"The phone line was out' Minot resident Jennifer Johnson told the Bismarck Tribune a few days later. "The only thing on the radio was music. No one was telling us what happened or what to do. We were trapped."

Cautionary tale

It could have been a lot worse in Minot. In the end, only one resident died. But the story encapsulates what relaxed rules have done to radio: the ceding of local control to distant, unresponsive owners with only the most tenuous ties to the communities they serve.

"What's happened to radio can serve as a cautionary tale for the rest of media that use the public airwaves," says Jenny Toomey, executive director of the Washington-based advocacy group Future of Music.

What's happened to radio can be summed up in a single word: consolidation. Toomey and her fellow romantics have done a good job documenting consolidation and its effects. The radio industry, which after all relies on a finite public resource, was a creation of the 1934 Communications Act, which in turn was written to ensure localism and diversity of content. Since 1996, consolidation has moved the industry in the opposite direction.

Two companies, Viacom Inc. and Clear Channel, now control markets covering half the country's radio listeners. Clear Channel alone has gone from owning 40 stations before 1996 to more than 1,200 today. The situation is more severe in smaller markets.

According to Toomey's calculations, "the largest four firms in most small markets control 90 percent of market share or more."

Deregulation advocates say consolidation does indeed foster greater experimentation and diversity. They cite airtight economic theories proving why this must be so. And sure enough, according to a study by Bear Stearns, the number of "core formats" used by radio stations - from "Urban Adult Contemporary" to "Christian Contemporary" -- has risen by 7 percent since 1996.

As Clear Channel Chief Executive Lowry Mays put it in congressional testimony earlier this year, "Owners with several stations are better able to diversify their programming to serve the variety of demographics that are present in the market."

Identical formats

So goes the theory, anyway. But this claim by the industry is really sleight of hand. An ingeniously constructed study of industry data by Future of Music demonstrates that many formats share nearly identical playlists, so that two stations with supposedly different formats will in practice be broadcasting indistinguishable content. The diversity is an illusion.

Among the radio romantics are a number of conspiratorialists who speak darkly of the public airwaves falling prey to a cabal of corporate villains intent on manipulating the flow of news and ideas; these arguments are particularly popular as the FCC considers relaxing ownership rules governing TV and newspapers.

But the real problem with consolidation isn't mind control -- it's mediocrity. In maximizing profits, large companies lower standards to the most easily accepted, and hence least interesting, quality of content.

As a consequence, a terrible sameness has pressed itself down on American radio. Many musical genres -- bluegrass, classical, jazz -- are quickly disappearing from the airwaves as this public resource is placed under control of a handful of broadcasters.

In the larger media world, bristling with satellite programming and round-the-clock cable and the downloadable dreck of the Internet, radio is small potatoes. Nationwide, radio gets only about 8 cents of every advertising dollar.

Yet it retains an importance out of proportion to its commercial muscle. Being highly mobile and nearly ubiquitous, following us from living room to car to shopping center, radio is woven into people's lives in a way matched by no other electronic medium.

And its appeal traditionally has been local. A homegrown radio station binds a community together as a good newspaper does. Its loss to a distant and out-of-touch proprietor can have unforeseen consequences.

They learned about that in Minot, on the morning of Jan. 18,2002.

Andrew Ferguson is a columnist for Bloomberg News.