Alexis González walks slowly and with some hesitation, using the outside wall of his house for balance.

"I'm getting used to the prosthesis（假体）," the 16-year-old says. He tries to smile, but an expression of sadness quickly returns to his face.

When he was 15, González made a decision that would forever change his life -- to leave Omoa, an impoverished（贫瘠的） village in Honduras （洪都拉斯）-- with dreams of getting to the United States.

At the end of the trek（长途旅行） -- about 2,500 kilometers (1,500 miles) across Mexico and Guatemala（危地马拉） -- he saw hope, school, a job and the chance to send money home. "Sometimes we don't even have food to eat and I also wanted to get a higher education," González says.

His mother was singlehandedly（单独地） raising nine children, working odd（零散的） jobs in restaurants and the nearby fields. They lived in a single room, an adobe（黏土） house with dirt（尘垢） floors built on a steep（陡峭的） and muddy（泥泞的） hill. Chickens being raised for food roamed（漫步，徜徉） around the structure. González says his father left the family when he was little boy.

When Gonzalez left in January 2014, he didn't ask his mother for permission. He only left a letter telling her about his plans. "I wouldn't have let him go," his mother Mercedes Meléndez says. "When he left I went looking for him everywhere." She even went to Corinto on the Honduras-Guatemala border（边防警卫） to ask authorities if they had seen him, she says.

González says he traveled by land through Honduras and Guatemala with a teenage cousin. They took the bus and also walked and hitch-hiked （免费搭便车）in some places.

Once in Mexico, they got on the cargo （货物）train migrants call "The Beast." Migrants get a risky, but free ride clinging to the outside of the train. Violent （暴力的）gangs （劫匪）sometimes board the train to rape（强奸）, rob（抢劫） and kill migrants.

Those without money to pay off（买通） the gangsters are thrown off, sometimes to their deaths in deep ravines（沟壑） or sharp rocks.

González says he never faced any gangs. Things seem to be going well for him and his cousin for a while. They had been traveling for a few days on the train and were excited at nearing the U.S.-Mexico border（边境） and crossing into the land of their dreams.

But they were also tired. They ate what they could, but were unable to sleep for more than an hour at a time. They were hanging onto the grate（炉膛） above the train car's couplers. "We used our own sweaters to tie ourselves to the train so we wouldn't fall off," González says.

But tragedy was just around the corner. Somehow, he doesn't know how, he fell off the train while sleeping. He woke up bleeding profusely（大量地）. "The train had severed my right leg and part of my left heel（脚后跟）," he says.

He was eventually rescued by the Mexican Red Cross and taken to a hospital where he recovered for a month. He stayed at a shelter（庇护所） for wounded migrants for another two months. There he was fitted with a prosthesis （假体）free of charge.

It's not difficult to find stories of minors in Central America who have lost limbs（肢体）, been kidnapped（绑架） or died while trying to travel through Mexico with the dream of migrating to the United States.