What inspired you to take on the story of Enrique's Journey?

A woman, Carmen, who would come and clean my house twice a month. She told me that she had four children that she had left behind in Guatemala and had not seen for 12 years. About a year later, her son made the journey to the United States and described to me El Tren de La Muerte, the Train of Death. I found it unbelievably moving: the story of children wanting, at all costs, to be with their mothers and going through these dangerous and terrifying worlds to reach them.

It sounds like your own research was pretty dangerous, too.

I wanted to put readers on top of the train with Enrique and to make them feel that they were alongside him. To do that, I had to retrace his journey myself. I did it the way he did it. Where he rode buses through Central America, I rode buses. And where he boarded the train in southern Mexico, I did, too. But there were times when I was afraid. There were too many close calls. There were times when I was filthy or I couldn't go to the bathroom for hours or was excruciatingly hot or cold or pelted by hail.

What was the most dangerous thing that happened to you?

A branch hit me square in the face while I was on top of the train and I almost fell off. That was pretty harrowing.

It seems like many of the mothers are not prepared for how their departure will affect their children.

A lot of these mothers believe in their hearts that they are doing the best thing by leaving their child. [Because the mothers send money back home] their child will not grow up in such grinding poverty. But the reality is that in most cases the separation lasts much longer than the women believe [it will], and the children ultimately resent their mothers for leaving them. So in the end, for many families, it's a sad story.

It seems like a difficult pattern to break, though, because the poverty is so devastating.

Some of the families live with a tarp over their heads and a dirt floor underneath them. Women describe not having anything to give their children for dinner and giving them a glass of water with a teaspoon of sugar toquiet their bellies. The level of poverty is staggering.

How has writing this book changed your opinions about illegal immigration?

The main change for me has been to recognize that such a powerful stream will only change if it is addressed at its source, if the economies of these countries that are sending large numbers of people to the United States improves. I talked to one kid in southern Mexico who had made 27 attempts to reach his mother in the United States, and he was getting ready to make attempt number 28. You come to believe that no number of border control guards is going to stop someone like that.