DALLAS -- The U.S. Department of State says 90 percent of the drugs that come to the United States pass through Honduras and Guatemala. And scholars and immigrants say the southern borderland, where Mexico shares a 700-mile border with Guatemala, is basically a sieve.
The combination of potential income generated by drugs and the lack of border discipline lays the foundation for the unrest that moves children north, says Adam Isacson of the Washington Office on Latin America (WOLA).
Last February, Isacson traveled to Central America to analyze the reasons behind immigration from Central America to the United States.
At the Suchiate River, on the southern lip of Guatemala, he found no border guards and no passport checks -- in essence, nothing to stop the flow of people, goods, and drugs into Mexico, and ultimately, the United States.
"[The Guatemala-Mexico border] is a place where there's a lot of criminality, a lot of trafficking of many things -- drugs, arms, and people," Isacson told News 8.
The money generated from drugs, the violence spun off from a virulent criminal culture, and the geography of a leaky border combine to create motives for Central American children to leave their homes.
The way they flee to the United States are also determined by money and geography.
The safest way for a child to go north is by bus with a human smuggler, known as a coyote. But that is also the most expensive way north.
Immigrant children in Dallas have told News 8 their relatives pay between $4,000 and $7,000 for a coyote escort.
"If you're going to take the road network, you're going to need money," Adam Isacson said. "You need a smuggler who has the route wired, who's able to pay bribes, who has safe houses."
It's cheaper and faster to hop a freight train.
That means clinging to the top of a rail car for 20-to-50 hours exposed to the elements, and vulnerable to extortionists, rape, physical torture, and removal from the train.
"In order to get on, you have to have U.S. money. You have to have a hundred dollar bill," Isacson said. His comments are backed up by other immigrants we've talked to. "And you have to have a hundred dollar bill for every couple of hundred miles on the train track that you're on. A new gang is going to demand payment not to throw you off."
The routes are so well known, travelers know where to hop the trains, and where to change lines to different border destinations. Two stops - one near Tierra Blanca near Veracruz and another near Mexico City - are especially treacherous, immigrants tell us.
Although the trains are well-known conduits for undocumented immigrants, they are not patrolled by Mexican police.
"I never got a good answer on why the Mexican authorities don't guard the trains," Isacson said.
The trains terminate at Juarez, Nuevo Laredo, and Reynosa.
Next stop, Texas.