exican-spotting isn't easy, even for an old hand like Terry Odom. Even if, as she has assured me, there are parts of Greenville, South Carolina, that are "just like Juárez." As I discover, you don't need binoculars or a field guide. What's called for is a good internal radar that can detect Latino immigrants a mile away.

Odom, who heads the South Carolina Committee for the Preservation of American Nationhood and Sovereignty, has planned a Saturday rally in the public library to discuss her town's immigration problem. She and her husband, David, are thrilled that I'm interested in her work, and they're driving me through town on a Friday afternoon expedition meant to showcase the cause. She promises me an immigrant bonanza.

"We are overwhelmed with Mexicans," says Terry. "They're taking over everything. I'm a patriotic American. I love America. And I can see that we're going to be a Third World country if we don't do something about this."

Odom, a tiny, rapid-fire woman, spent her childhood in Texas, where her father was a border patrol agent and her mother managed a Mexican restaurant serving mostly Mexicans. David, a country boy raised in Greenville, is a deeply religious born-again Christian with a soft, fleshy face and shy smile. He sits quietly in the back seat, anxious to talk whenever he has the chance.

I've come to Greenville because the Odoms, like many in the immigration control movement, believe that among the litany of evils the Latino immigrants are visiting on their community and the world are crimes against the environment. "They've taken over our parks," Terry tells me. "We have a park a block from us. We couldn't even get near it because of the Mexicans."

It's a theme I've also heard from the large, national anti-immigration groups. I'm here to see firsthand how the issue plays at the grassroots of the movement and to find out whether the environmental concerns of anti-immigration groups are genuine -- or just a smokescreen for their real agenda.

But the Odoms, as I come to understand, believe I'm in Greenville to witness and report on the Mexican hordes. Generous, gregarious, hospitable Southerners, they assume the role of guides on an African big-game photo safari, leading me into the field to hunt the quarry down. We're driving along White Horse Road, the main Mexican habitat. But late Friday afternoon is apparently the wrong time of day, and we're not having any luck at all. Even with Terry's Mexican detection radar set on high, the Latinos invading Greenville are in hiding.

Green Themes

"This country -- thirty years after it decided it had to restore and protect the environment -- added over 30 million more people we had to deal with for air pollution [and] water pollution," says Roy Beck of NumbersUSA.

Beck, a ubiquitous figure in the anti-immigration movement, has arrived in my living room via video, in his widely circulated presentation on immigrants and population issues. A nerdy character with thin, brown, conservatively cut hair and wire-frame glasses, Beck worked as an environmental journalist for several years. He has now devoted himself full-time to the cause of convincing people that immigration is a big, big problem, and environmental arguments are a core element of his repertory.

Because of immigrants, the virtual Beck charges, "we have had to...build twice as many sewage treatment plants, build twice as many roads and streets." Ominous music plays at several points in the video, over a shot of a sort of population odometer with the numbers rolling ever higher. How, Beck asks, will the country cope with future growth "if at this population 40 percent of the lakes and streams in this country still are not fishable and swimmable?"

Beck is hardly alone in sounding the immigration/environment alarm. The Federation for American Immigration Reform (FAIR), Carrying Capacity Network, Population-Environment Balance, and many others all argue that immigrants should stay home to protect U.S. natural resources -- and the entire global environment. The reasoning is that most immigrants come from less technologically advanced countries, where they consume less energy and fewer commodities and thus, says FAIR, tend to "deplete and damage the earth's resources more slowly...than U.S. consumers."

That's accurate as far as it goes. The United States, with 5 percent of the world's population, is responsible for at least 20 percent of global environmental damage as the result of fossil fuel consumption, deforestation, acid rain, and emission of ozone-depleting substances. Anti-immigration groups consider that fact justification for keeping would-be immigrants in their homelands, where their standards of living will remain low, rather than allowing them into the United States to consume more natural resources. In other words, leave injuring the planet to Americans.

But the environmental issue that most exercises immigration reform activists is suburban sprawl. FAIR calls it "one of the most daunting environmental problems facing humankind."

In 2000, during a period of debate over immigration visas and amnesty provisions, FAIR and other groups mounted an anti-sprawl campaign. It included print and broadcast advertising in South Carolina and the District of Columbia blaming "runaway population growth" for traffic congestion, overcrowded schools, and loss of farmland. (One estimate placed FAIR's 2000 ad budget at $12 million.)

A NumbersUSA ad in the Washington Post showed a photograph of a congested highway with the headline "Don't Get Mad at the Traffic. Get Mad at Congress." And in 2000, Don Chen, director of the anti-sprawl group Smart Growth America, began seeing tables at land-use planning conferences that were staffed by immigration reform advocates.

Then there's the special green version of Roy Beck's 1998 video, "Immigration by the Numbers: An Environmental Choice." It features an introduction -- replete with footage of wildlife and nature scenes on the one hand, backhoes and construction on the other -- by a woman named Monique Miller, executive director of a now defunct group called Wild Earth, standing in a deep pile of snow. "Americans are worried about sprawl," says Miller. "And the primary cause is population growth. No matter how well we manage that growth...it inevitably leads to more sprawl and congestion."