Border lines: the path to the American Dream is fraught with danger, mud and running in the dark.

Run, here comes the border patrol! Run, run! ... One's body simply reacts to the words in a nearly superhuman dash to get away. We jump into an open truck bed. Then we run as fast as possible over broken, rough scrub and bushes. The speed of our escape is gazelle-like. Our legs don't respond well in the bone-chilling desert cold, and it's nearly totally dark out. That's how it began, the nine of us running and trying to get across the U.S.-Mexican border.

It takes good camouflage to hide in the dry, prickly desert scrub, all the while evading U.S. border agents. It's impossible to breathe fast enough and your heart pumps madly for lack of oxygen, beating like a demon trying to escape from inside your ribcage. A waning moon and the rough terrain make it impossible to move without risking a fall. The border agents seem to have retreated; we can no longer see the flashing red and blue lights of their vehicles. A woman and I have tripped into some mud and sunk down into it up to our knees. It's every man for himself to get across the border.

Yet a fellow border-crosser comes and pulls me from the muck, I start running again, but now everything is heavier because of the mud. Yet we have to stay quiet since any noise could be picked up by the officers, ending instantly our dream of getting across the border intact and undetected. Your learn quickly to swallow the urge to scream, despite running through branches that hurt your face and arms.

Everyone down! yells our handler. We throw ourselves on the ground. see my companions scattered about. hiding, in total silence until shortly a gruff voice in the distance rings out: "We have the area surrounded. It's better you come out." A border agent is talking through a bullhorn to us. A bright beam of light begins to pan across the desert in search of bodies, shadows, small movements, life.

"Who is the mother of this child?" barks an agent. Nobody answers. A few seconds later a gun goes off. Our hearts freeze as the roar of gunshots rattles in our eardrums. Yet we have to be silent, not knowing what will happen next or where the bullets are being aimed, or if any of us have been hit. The gunfire continues in the air and the body of child falls down into a narrow pass.

I am shaking with fear. My leg hurts. Yet I have to swallow the pain because any tiny movement is the difference between making it or being captured. A woman to my side looks at me, and I can see in her eyes that she is struggling with the same thoughts. With a slight glance my eyes beg her to not move. Any little nudge will cause a dry branch to crack or a bush to waver, and it will all be over for us.

"The desert is full of dangerous animals, so come on out, we have you surrounded," shouts a border cop, his voice now much farther away. A long time passes, but we remain there, petrified. Our handler has given us orders to stay hidden until we are certain the agents are very far away.

Moving again. Carefully, we begin to walk down a path. We now have to cross a very narrow gully and do it lying flat on our bellies. Walk, now faster, now run: We spend hours in this routine. Two of my group fall when they slip climbing a mountain we're trying to get over. There's a short break to rest and drink a little, trying to quench the horrible thirst that comes from running. We reach a riverbank. Our handler tells us to pick up two stones. We should toss aside the one that gives us bad vibes and, with the one that's left, the one that feels lucky, make a wish.

We continue walking until we reach a tunnel. The border patrol is there. We squeeze down into the underground and hold our breath. The agents are very close. Once they pass by we continue to move. Here comes a troca, "truck" in Spanglish, the common tongue in the borderlands. We're saved! It's the truck that picks up immigrants and takes them on to their final destinations. We all jump quickly into the bed. But our relief is short-lived. The border agents are back on our trail.

Running again. The biggest risk is hurting your legs, since jumping down to the ground is hard. The ungodly searchlights and the bark of megaphones are nightmarish. But they are gone, this time for good. Our handler stops the chase and brings us back to form a circle. "We've made it eight kilometers in two and a half hours," he says. "This is nothing compared to what migrants really face when crossing into the United States. I have spent up to 15 days hiding from the border patrol."

And that's the story of my experience in a simulation of what it's like to cross the most congested border in the world, one crossed by 1,500 Mexicans a day, 557,000 of them a year, according to the Mexican Populations Council. Approximately 590,000 Mexicans are forecast to leave their country each year by the end of the decade. The experience of crossing the border, although a simulation, is surprisingly realistic.

Parque EcoAlberto, 170 kilometers from Mexico City, offers the tour. They've been doing it for two years as an homage to those who have died attempting to cross into the United States seeking a better life. The park also has camping areas and hot springs. The idea is to use nature in a sustainable manner and to create jobs, even if it's just a few, to help stem economic immigration.

Suffering. A 1,600-hectare park, EcoAlberto was created by the Nhanhu Indians in Hidalgo state in order to improve the lives of people in El Alberto. It was done using money earned on the other side of the border. Of the town's 2,000 inhabitants, 90% have illegally migrated to the United States.

The night crossing tour can only be done in groups of 20 people at a cost of US$13 each, a very low price when you consider what it takes to create such a production and the number of people involved, 72 of them. The mission is to impart to visitors, without harming them, a small sense of the suffering people go through to get to the United States.

EcoAlberto is a good model for recreating the U.S.-Mexico border. It has a wide variety of microclimates, from pure desert to damp. It's normal to see snakes on the tour. There are coyotes, foxes, badgers, rabbits, squirrels and lots of different birds.

The end of the journey is mystical, magical, relaxed--beyond words. Absolutely the farthest thing from the tough scramble of a border crossing. But the less said the better, in the custom of the Nhanhu: You really have to live it to understand it.

MARISOL RUEDA * EL ALBERTO, MEXICO