Guardian of the Green Card

They sit on lawn chairs perched on hilltops or in the brush, armed with night-vision goggles, walkie-talkies and guns. Mercer's is a .45-caliber Colt. She holsters it in a custom gun belt with leather loops to hold bullets, like a bandoleer.

But it has become harder to find time for patrolling. Mercer is vice president, chief fundraiser and national recruiter for Minuteman, as well as director of the Tucson chapter. The group started less than a year ago with 400 members. Now, she estimated, they have signed up 8,000.

She said that part of the solution would be a tall, concrete wall erected along the entire 2,000-mile Mexican border between California and Texas.

"All they have to do is secure the borders," she said. "We won't have fear of terrorists coming across. We won't have fear of the sex-slave trade. We won't have criminals crossing."

Noticing a young man in an Army uniform struggling under a pile of green bags in the rental car terminal, she dashed to hold open the door for him.

"He's going to Iraq," she said, returning to her seat. "I love soldiers. They're our protection. They should be on our border."

Demanding Green Cards

At the Holiday Inn in Alexandria, a man with a Jamaican accent helped check in Mercer, who has a slight accent of her own. Outside, where taxis lined up four and five deep, the accents of the drivers were those of the Middle East and Africa.

"It is very hard to survive here if you want to live in a proper place," said cabby Khalil Siddiqui, 48, who has a master's degree from a university in Pakistan and is a naturalized U.S. citizen.

The corner gas station three blocks away was staffed by a man from Pakistan and two women, one from Ethiopia and the other from India.

"Foreign people are hard workers," said Tahir Younis, 28, the mechanic. "You go to McDonald's, and who works there? Foreigners. If there were not foreigners, what would you do?"

At a nearby fast-food restaurant, a 21-year-old woman mopped the floor. She chatted openly in Spanish, until the topic of a green card was raised. Then she lowered her head, hushed her voice to barely a whisper and said she could no longer speak because she had to return to her work.

When Mercer last visited Washington in May, she said, she and another Minuteman asked the drivers of all the cabs they took whether they were citizens. If they said they were not, Mercer and her colleague asked for their green cards. Mercer said they wanted to prove a point and did not report anyone to immigration authorities.