Central Americans Traverse Mexico On Grueling Journey To U.S.

IXTEPEC, MEXICO - AUGUST 04: Immigrants arrive for a rest stop after a 15 hour ride atop a freight train headed north early on August 4, 2013 in Ixtepec, Mexico. Thousands of migrants ride atop the trains, known as 'la bestia,' or the beast, during their long and perilous journey through Mexico to the U.S. border. Many of the immigrants are robbed or assaulted by gangs who control the train tops, while others fall asleep and tumble down, losing limbs or perishing under the wheels of the trains. Only a fraction of the immigrants who start the journey will arrive safely on their first attempt to illegally enter the United States. (Photo by John Moore/Getty Images)