RealAudio 2.0 14.4

When most people travel between the United States and Canada they pass through a port of entry, staffed by customs agents. But in between those ports of entry are thousands of miles of farmland and woods, often called the longest unguarded border in the world. It's inviting for a growing number of people entering the US illegally.

The US Border Patrol is charged with monitoring all that empty space. But with thousands of miles and only a few hundred agents, it's a tall order. In Minnesota and North Dakota, 22 agents based in Grand Forks struggle to cover 917 miles of border and eight surrounding states. Those agents are hard pressed to stop illegal traffic.

Zimmerman: My wife will be the first to tell me I don't work eight hours days. Twenty-two hours one day and come back and work 18 hours the next. I guess we all kinda bleed green up here. You don't see many of us transferring anywhere.

But the job can be frustrating. He's doing what's known as cutting sign - looking for tracks across the border. They're easy to see - it's muddy after several days of rain. Several vehicles have crossed in his sector since he last covered the area a couple days ago. About all he can do is note the intrusion in his logbook.

Zimmerman: When did it come in - last night, this morning, two days ago? It's an open border, and the people who come through here are working under that premise. It's an open border. They're rarely ever apprehended.

Just who is crossing the border illegally? A growing number of illegal aliens and drug smugglers are the most common intruders. But there's also parrot smugglers, farm chemical smugglers, and terrorists.

The Grand Forks sector arrested nearly 2,000 illegals last year. Assistant Chief Patrol Agent Lonnie Schweitzer expects that number to grow.

Schweitzer: We already have intelligence on Mexican citizens who fly to Canada and attempt to enter the US through the northern border, because there's no visa requirement in Canada. All you need is a passport.

Schweitzer: The Royal Canadian Mounted Police seized 4,500 marijuana plants in a high-tech grow operation. Between $5 million and $7 million of production a year. Were they selling all that in rural Manitoba? I don't think so.

The open border is also reportedly catching the eye of an even more dangerous kind of criminal. Lonnie Schweitzer says a couple years ago his office caught two major-league international terrorists.

Schweitzer: This was the number one and number two wanted people in India. Sikh terrorists. There were 29 deaths attributed to one person. They were now moving a husband, wife, and child through Minneapolis and up through Grand Forks to Winnipeg, into the East Indian community. We arrested those people right in Minneapolis-St. Paul.

As pressure increases on the northern border, the Border Patrol is putting more money into closing some of the open doors. Lonnie Schweitzer expects more agents to be hired in the next few years. Right now a lot of money is being put into high-tech solutions.

Schweitzer: This here's a sensor. It don't walk, it don't talk. An antenna goes here. It's buried out on location.

Another new tool is thermal imaging.

A small camera that detects heat turns atop a patrol vehicle as electronics technician Stuart Chapman works a joystick in the vehicle. He points out the image on a small television mounted on the dash.

Chapman: About a mile. You'll be able to discern a walking individual. There's Agent Schweitzer. It's sensitive enough you even get some idea of the features. You can even see the heat signature left by his hand on the glass.

Zimmerman: There's a sleeping bag, survival parka, two shovels, fire extinguisher, snowshoes, backpack, tire chains....