It was a bomb that started the whole thing–an image of one anyway. A nationwide controversy erupted in July after Clear Channel Communications, one of the country’s largest outdoor advertisers, refused to run an antiwar ad paid for by Project Billboard, a Berkeley, California-based nonprofit. The ad, which was supposed to appear on a billboard over Times Square during the Republican National Convention, featured an image of a bomb and the slogan “Democracy is best taught by example, not by war.” Clear Channel said New York, in the aftermath of 9/11, is no place for a bomb image. Project Billboard sued for breach of contract. Critics accused Clear Channel of political censorship, equating the incident with the company’s decision to fire shock jock Howard Stern after he repeatedly criticized the Bush Administration.

The two sides eventually settled, and Clear Channel is now running the ad, although with a dove replacing the bomb. But the billboard flap raises lingering questions about Clear Channel’s control over outdoor advertising, a little-studied but important dimension of its media empire.

Billboards were the object of public derision for most of the twentieth century, particularly since the 1960s, when a national movement emerged to fight their proliferation along scenic highways. Nonetheless, in the past twenty years the outdoor advertising industry has become a multibillion-dollar behemoth, evolving from basic highway signage to more than 1 million multimedia displays targeting consumers in trains, buses, taxis, schools, airports, shopping malls, concert venues and stadiums. The growth spurt, which accelerated between 1996 and 2000, has followed a pattern of consolidation similar to other media. Just three companies now dominate the landscape: Viacom, the already bloated media empire; Clear Channel, the largest owner of radio stations in the United States; and Lamar Advertising, an advertising-only company that acquired 538 outdoor advertising companies beginning in 1997.

Outdoor advertising, unlike other forms of media, is not regulated by the Federal Communications Commission. Instead the task falls to the antitrust division of the Justice Department, which enforces general guidelines over market control and ownership. But critics say the department has not done enough to stop consolidation. “They do not appear, for whatever reason, to be acting in connection with outdoor advertising,” says William Brinton, an attorney on the board of Citizens for Scenic Florida, a billboard watchdog group based in Jacksonville. “Watching the consolidation over the past six years, I once mused about taking out an ad in the [New York Times] under ‘Lost and Found’ and inquiring if anyone has seen anyone from the Antitrust Department,” Brinton writes in an e-mail. To date, no Congressional legislation has been introduced to address consolidation in the industry.

The Big Three now control anywhere from 50 to 75 percent of the entire industry, according to some estimates. In San Francisco, Clear Channel and Viacom together control about 90 percent of the outdoor advertising space. The Big Three also raked in 85 percent of the $5.5 billion spent on outdoor advertising in 2003, with Viacom grabbing $1.7 billion, Clear Channel $2.17 billion, and Lamar $810 million. Clear Channel’s share alone accounted for nearly 40 percent of all sales, making it the industry leader for that year. The company boasts that its displays, which total more than 150,000 in the United States, can reach over half of the total population, 75 percent of the Latino population, and seven out of every ten airline travelers. Clear Channel displays appear in every major US city, with more than 11,000 in New York City alone, where the company owns more than half of all the billboards in Times Square.

Industry officials say consolidation promotes competition and creativity. But critics say massive proliferation, coupled with oligarchic ownership, is destroying the diversity of local communities. “They homogenize, just like fast-food operations when they all look alike from place to place. There’s a sense that you could be anywhere,” says Meg Maguire, president of Scenic America, a Washington, DC-based nonprofit that tracks billboard proliferation. Concentration in the industry also has potentially deleterious effects on civic discourse and diversity of opinion, media critics say. “The more space they take up, the more cultural and social influence they wield,” says Mark Crispin Miller, a professor of media ecology at New York University. “And if [the companies] are, for example, very close to the government, they function as a de facto propaganda machine for that government. That’s neither culturally advantageous, nor is it healthy in any civic sense.”

Outdoor advertising currently represents only 2.6 percent of total US advertising expenditures, compared with nearly 75 percent for newspapers, television and radio combined. But in some ways, as Clear Channel Outdoor likes to boast, outdoor ads have a more powerful impact: “Outdoor is great because you can’t turn it off, throw it away or click on the next page. That means your message is reaching consumers everywhere–all the time, every day.” Yikes.