At its peak a few years ago, more than 17,000 people streamed into town, united in their effort to shut down the School of the Americas, a United States Department of Defense center that they believe has trained Latin American military leaders to torture and murder.

Hundreds of people would cross onto the base and get arrested in mass acts of civil disobedience. Catholic groups staged workshops. Old lefties treated it like a family reunion. Vendors sold bumper stickers and Guatemalan hacky sacks.

So many people from so many left-leaning organizations began showing up that School of the Americas Watch, which runs the protest, rented the local convention center for seminars and concerts.

Enterprising locals set up barbecue stands and charged $10 for parking in nearby lots. The convention bureau helped with hotel arrangements.

The protest has brought the city as much as $2.2 million in business, more than twice what the annual Jehovah?s Witness convention did, said Peter Bowden, president of the Columbus Convention & Visitors Bureau.

?It is, in essence, the equivalent of a fairly large convention for our town, and we tend to treat the attendees in that respect,? Mr. Bowden said.

But the times, they are a changing. This year?s protest, the 20th, drew its smallest crowd ever over the weekend. Both the police and organizers agree that fewer than 5,000 people showed up.

Signs of its decline were everywhere. At the Masonic lodge near the protest site, a local military family had hoped for a lucrative weekend selling hot dogs and drinks. They packed in 15 cases of water, but by Saturday afternoon only a dozen bottles had sold. They did not even bother on Sunday.

As a counterbalance to the protest, the school 10 years ago began offering tours over the same weekend and changed its name to the Western Hemisphere Institute for Security Cooperation. A panel of school leaders volunteers to answer questions and explain that the education of Latin American military personnel now emphasizes democracy and human rights along with military intelligence and psychological operations.

Last year, more than 500 signed up to attend, mostly students from Catholic high schools and colleges. This year, only 128 were bused on base for the 90-minute session.

The small crowd at the gates of Fort Benning disappointed Sheri Hosek, 39, who traveled from Dubuque, Iowa. She had heard about the event through her work with Franciscan nuns.

?There was a lot of hype about it, but it feels like a much smaller presentation than I had expected,? Ms. Hosek said. ?It feels more like a summer festival, a very liberal one of course.?

Maybe it was the economy, some said. Others said that rallying liberal activists after the election of President Obama had become more challenging because many thought the fight was over.

And it did not help that a couple of thousand Jesuit students who usually attend did not come this year, choosing instead to hold their annual teach-in in Washington.

Others wondered if Latin America politics just are not capturing the attention of American youths as they once did.

?My generation is all over the place,? said Ben Johnson, 28, of Athens, Ga., who was grabbing a coffee in a hotel lobby near the base. ?They are completely apathetic, or they?ve completely devoted their entire life to change.?

The protest began after six Jesuit priests, their housekeeper and her daughter were killed in El Salvador in November 1989 by a group that a Congressional task force connected to School of the Americas graduates.

On the anniversary the following year, a small group led by the Rev. Roy Bourgeois, a Catholic priest, held a water-only fast at the gates. He has since become an internationally known peace advocate and still lives in a small apartment near the gate.

?Most of the young people in the crowd don?t even know who he is,? said Liz Loescher, 68, an eight-time veteran of the protest who runs the Georgia Conflict Center in Athens.

Stiffer federal penalties have hurt the effort, too. In the late 1990s, almost 3,000 people crossed onto the base and were briefly detained. After the Sept. 11 attacks, when a series of fences were built, that number dropped to 80.

Then a federal judge began handing out six-month sentences. That sent the numbers even lower. Last year, only four people entered the base, the same number as this year. All were arrested and charged with federal trespassing.