People cross into Mexico, rafting across the Suchiate River from Guatemala, on August 2, 2013 in Ciudad Hidalgo, Chiapas, Mexico. Thousands of undocumented Central Americans pass illegally through Mexico, many of them immigrants on the first leg of their long and perilous journey north to the United States. #

A group of undocumented Guatemalans is ferried across the Suchiate River into Mexico on August 1, 2013 in Talisman, Mexico. They pass directly under a bridge with a Mexican immigration checkpoint. #

Lightning flashes across the sky as a freight train known as "la bestia," or the beast, prepares to depart Arriaga, Mexico, on August 3, 2013. Thousands of migrants ride atop the trains during their journey through Mexico to the U.S. border. #

Central American migrants climb atop a freight train headed north early on August 4, 2013 in Arriaga. Many of the immigrants making this journey 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. #

Undocumented Guatemalan immigrant Elvira Lopez, 22, stands on crutches at the Jesus el Buen Pastor shelter in Tapachula, Mexico, on July 31, 2013. She has been convalescing at the shelter for six months after falling under the wheels of a freight train and losing her right leg while en route to the United States. The shelter, which relies entirely on private donations, has helped countless immigrants recover from their wounds while helping arrange for prosthetics. Lopez said she fell asleep 5 days into her journey from Guatemala and was knocked off the train by a tree branch. #

Guatemalan immigrant Jorge Enrique, 33, spends an evening at the Hermanos en el Camino immigrant shelter on August 5, 2013 in Ixtepec, Mexico. He said he planned to ride a freight train later that night to continue his journey north to eventually cross into the United States on his way to Tampa, where he had previously worked as a house painter. #

Salvadorian immigrant Consuelo Miscuita, 42, and her daughter Wendy, 15, spend another night at the Hermanos en el Camino immigrant shelter on August 5, 2013 in Ixtepec, Mexico. Consuelo said before arriving to the shelter they were robbed of all their money by Mexican federal police. They have been staying at the Hermanos shelter for four months while awaiting Mexican immigration documents to allow them to safely travel to the U.S. border by bus. Once there, they plan to meet up with Wendy's father, who is currently working in the northern state of Sonora, and then try to illegally cross together into the United States. The women are trying to avoid riding the freight trains, known as "la bestia," or the beast, as thousands of other Central Americans do on their perilous journey north through Mexico. Some of the immigrants are robbed, assaulted or, especially in the case of women, raped by gangs who control the train tops. #

Honduran immigrant Jorge Vargas Aguilar, 18, spends a day at the Hermanos en el Camino immigrant shelter in Ixtepec, on August 5, 2013. He said he planned to ride a freight train north later that night to continue his journey to the U.S. border and eventually to San Francisco to find whatever work he can. #

Honduran transgender immigrant Daniela, 20, at the Hermanos en el Camino immigrant shelter in Ixtepec, on August 5, 2013. She has been staying at the shelter for more than a month while Mexican immigration authorities process documents to allow her to travel to the U.S. border via bus, a much safer alternative than riding the freight trains north. #

Honduran immigrant Melvin, 16, in the Hermanos en el Camino immigrant shelter in Ixtepec, on August 5, 2013. He said he planned to ride a freight train north later that night to continue his journey to the U.S. border and eventually to San Francisco to find whatever work he can. #

Honduran immigrant Ruben, 43, spends a day at the Hermanos en el Camino immigrant shelter on August 5, 2013 in Ixtepec, Mexico. He had previously worked in Orlando, Florida as a construction worker. He said that when he had saved enough money five years ago, he returned voluntarily to Honduras and was assaulted and robbed of all his savings, also suffering a serious injury to his right eye. Now, again journeying to the U.S, he said he planned to ride a freight train north to the border and eventually return to Orlando. #

Immigrants listen as Catholic Father Alejandro Solalinde Guerra warns them of the dangers in their journey to the United States, while at the Hermanos en el Camino (Brothers on the Road) shelter on August 4, 2013 in Ixtepec, Mexico. The shelter, founded by Solalinde in 2007, houses and feeds immigrants, mostly from Central America, during a stop on their train route through Mexico towards the U.S. border. #

Central American immigrants arrive on top of a freight train to the Hermanos en el Camino immigrant shelter in Ixtepec, on August 6, 2013. The sign outside reads "Welcome Migrants." #

The international port of entry stretches from the U.S. (right), into Mexico on May 21, 2013 in Hidalgo, Texas. The Rio Grande Valley area is an important international commercial zone but has also become the busiest sector for illegal immigration and a key drug smuggling route on the entire U.S.-Mexico border. #

An anthropology student marks the spot where human bones of a suspected undocumented immigrant were found by the U.S. Border Patrol on a ranch on May 22, 2013 in Falfurrias, Brooks County, Texas. In Brooks County alone, at least 129 immigrants perished in 2012, most of dehydration while making the long crossing from Mexico. Teams from Baylor University and the University of Indianapolis are exhuming the bodies of more than 50 immigrants who died, mostly from heat exhaustion, while crossing illegally from Mexico into the United States. The bodies will be examined and cross checked with DNA sent from Mexico and Central American countries, with the goal of reuniting the remains with families. #

A U.S. Border Patrol agent detains undocumented immigrants who had crossed from Mexico into the United States on April 11, 2013 in Mission, Texas. In the last month the Border Patrol's Rio Grande Valley sector has seen a spike in the number of immigrants crossing the river from Mexico into Texas. With more apprehensions, they have struggled to deal with overcrowding while undocumented immigrants are processed for deportation. #

A U.S. Border Patrol agent handcuffs an undocumented immigrant near the U.S.-Mexico border near Mission, Texas, on April 11, 2013. A group of 16 immigrants from Mexico and El Salvador said they crossed the Rio Grande River from Mexico into Texas during the morning hours before they were caught. #

Glegario Ramiriz, 44, poses for a portrait as he serves time in Maricopa County Sheriff Joe Arpaio's tent jail in Phoenix, Arizona, on March 11, 2013. Ramirez was arrested in Phoenix in November for drug possession. He said he had been living with his family in Phoenix and previously Los Angeles for a total of 34 years. As an undocumented immigrant with a criminal record, he may likely be deported to Mexico after his serving his sentence. President Obama's administration deported a record 1.5 million people during his first term of office. In 2012, 55 percent of deportees had criminal convictions for drug offenses or driving under the influence, according to U.S. immigration officials. #

An immigrant inmate exercises while another sits on his bunk at the Maricopa County Tent City jail on March 11, 2013 in Phoenix, Arizona. The striped uniforms and pink undergarments are standard issue at the facility, despite an ongoing court challenge. The tent jail, run by Maricopa County Sheriff Joe Arpaio, houses undocumented immigrants who are serving up to one year after being convicted of crime in the county. Although many of immigrants have lived in the U.S for years, often with families, most will be deported to Mexico after serving their sentences. #

Jose Rosales, 17, from Guatemala spends a night at the San Juan Bosco shelter for immigrants in Nogales, Mexico, on March 9, 2013. Rosales said that he had lived as an undocumented immigrant in Los Angeles for two years before he was deported. He planned to try and cross into Arizona with a "coyote" or human smuggler in the upcoming days. The Juan Bosco shelter, located in Nogales, Mexico close to the U.S. border, allows immigrants to stay for up to three nights, either after they have been deported from the U.S. or before they try to cross into Arizona. #

An immigrant from Guanajuato, Mexico spends a night at the San Juan Bosco shelter in Nogales, Mexico, on March 9, 2013. The man, 40, who preferred to not give his name, said he had been living in California for 14 years, working as a farm laborer. He said he was arrested by police after an argument with his spouse and then turned over to immigration authorities, who deported him a month later. #

Jorge Rodriguez, 62, from Guatemala, spends a night at the San Juan Bosco shelter for undocumented immigrants in Nogales, Mexico, on March 9, 2013. Rodriguez said he worked in the United States for 8 months before he was detained by immigration authorities and deported. #

American citizen Lace Rodriguez and her husband Javier Guerrero from Mexico, embrace with their son Javier Jr., in Nogales, Mexico, on March 10, 2013. The family lived together in Phoenix, Arizona before Guerrero, an undocumented worker from Mexico, was detained by the Border Patrol after being stopped for speeding and drug possession, held for three months by Immigration and Customs Enforcement (ICE) and then deported March 4 to Nogales, Mexico. Guerrero had lived in the United States for 17 years. He and Rodriguez, a medical student, have two children, and she is nine months pregnant with a third. The splitting up of families has become a major issue as the U.S. works towards immigration reform. #