Arriaga, Mexico (CNN) -- The ground rumbles when it moves. The steel wheels grind and screech. The whistle is a snarl not a toot. Some call it the "train of death," others simply call it "La Bestia," or the "the beast."
To thousands of dirt-poor migrants, this thundering cargo train is a free ride to their American Dream -- or their modest dreams of working hard and saving even harder to send a few dollars home to loved ones.
But along the ride, migrants who cram onto the roof of the trucks and any spare space in between risk death and injury.
One of the riders is a Honduran widow, Nolbia Pacheco. She tells me the day she left her 6- and 11-year-old children with her cousin, she simply said she was going "to the other side." She did not explain what she meant or how long she would be away.
"I told them I was going to the other side, so that they could be somebody in life, so they had a chance to study and could live better," Pacheco said as she set out on the train at the railhead in Arriaga, a Mexican town about 200 kilometers (125 miles) from the border with Guatemala.
"Of course I miss them. But I can't go back, life is too hard in Honduras and I can't find work," she added.
Like many others, Pacheco said she hoped to get work washing dishes, picking vegetables, in construction or "whatever."
The Salvadoran Consul in Arriaga, where "The Beast" begins its journey through Mexico, is Vilma Mendoza. She says more than 20,000 illegal migrants have boarded the train in the first four months of this year.
On the first leg of its journey the train lumbers 12 hours along the coast to the city of Ixtepec, in Oaxaca state, hauling corn, cement and minerals.
From Ixtepec migrants jump onto other cargo trains, heading first to Mexico City then onward to various points on the Mexico-U.S. border. It's a journey that takes days or weeks. And it's treacherous.
They're driven on by poverty at home. But in "El Norte" (the North), the name they give the United States, they know they stand a chance of earning five or six dollars an hour. Back in Guatemala or Honduras, they say, they'd have to work an entire day to earn the same.
Human rights groups estimate thousands of migrants have died after falling off the train, due to fatigue, dehydration or attempts to board while it was on the move. Thousands more have fallen under the wheels and lost legs or arms -- and in some cases both.
Even if they manage to cling onto the train, the route north is fraught with risk.
Government human rights workers say criminal gangs and corrupt immigration officials and police regularly prey on the migrants, robbing them, raping them and kidnapping them.
Fernando Batista, a Mexico City-based senior official at the government National Human Rights' Commission (CNDH), said in a six-month period last year 9,700 Central American migrants were reported kidnapped.
He said kidnappers rob their victims first. They then demand the phone numbers of family members in the U.S. or back in Central America and demand wire transfer ransoms, usually between $300 and $500 dollars.
"The migrants are extremely vulnerable. And there are cases where federal and local authorities, far from doing their job of preventing crime, are colluding with those people committing those crimes," Batista said.
According to Mendoza, the Salvadoran consul, around 30 percent of those who take the train are "cyclical migrants", men and women trying to return to the U.S. after previously being deported, or making a fresh attempt after failing before.
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Guatemalan Antonio Guzman is a returnee. He was deported from Michigan two years ago. Once again he has left his wife and four children behind and set out for "El Norte."
"I know they will be better off if I can make it," he says. Guzman is proud to say that he is a hard worker and proved that on his last stay in America.
"I worked all the jobs in the kitchen in Applebee's in Michigan. I started washing the dishes and then became the chef's assistant and made the salads," he recounted.
"Then one day when all the staff voted, they chose me as the employee of the year. And they put a plaque up in the lobby. It felt good because I looked and there was only one Hispanic name and it was mine," he beamed.
He's heard that animosity toward illegal migrants is growing in the United States, with tighter laws particularly in Arizona and now more recently in Nebraska. But he has only good memories of his previous time in the United States.
"The Americans I worked with were great," Guzman said, adding that once when he damaged his knee and couldn't work his co-workers at Applebee's collected cash to send home to his family.
Honduran Greville Bueso is a first timer. He's traveling alone and says he has no money. All his possessions fit in a small backpack, with space to spare. He's carrying a light jacket, toothpaste and a toothbrush. Along the way he says somebody donated him an old AC Milan soccer shirt.
He's seen America in the movies and heard stories from other Hondurans.
"I've heard people saying nice things about America like it's another world. So I want to see for myself and try my luck," Bueso said.
In contrast to his hope, others are distrustful of the "American Dream".
"The American Dream died a long time ago. It's a utopia," said the Salvadoran consul Mendoza. "It really means getting some kind of economic stability even if that means breaking up families and being separated from the people you love.
"It's a mirage. How can it be a dream to arrive and work long hours and be scorned by others and live all crammed into one house," she said.
Elvin Chinchilla, a 26-year-old Guatemalan migrant, strongly disagrees. He's trying to sneak back into the United States. He was jailed on a drunk driving and a drug charge and later deported. While he was in jail, his Mexican-born wife gave birth to his baby daughter.
"The American Dream is really the American Dream. You can earn good money and live better," he said, explaining he had never been able to buy a new pair of sneakers until he first arrived in America 6 years ago.
In Ixtepec, Catholic priest Alejandro Solalinde set up a hostel five years ago. He gives migrants a free meal and a free bed, as they pass through.
Solalinde has a kindly face but blames free market capitalism and bad government for crushing the economies of central America, thereby forcing its inhabitants to head elsewhere in search of a brighter future.
He also believes Hollywood has sold the world a rosier-than-reality image of what life is like in America.
But as he says goodbye each day to the migrants he has helped, Solalinde seems to draw some comfort from their determination.
"This is an interminable exodus. It never ends. But I'm sure they're going to make history," he said. "They're going to rebuild America, and maybe it will be an America with a Latino heartbeat."