." >> reporter: in the city of salteo, thousands of rail cars carries goods made in mexico north to the u.s. they also carry migrants from central america on their 1100-mile journey from mexico's southern border. in it salteo, most will hop off for the final leg of their journey north, trying to avoid detection not just by mexican and u.s. authorities but also criminal gangs. many will attack a brief respite at casa dterks les if migrante, started by a jesuit priest. the migrants may be violating the law, but the priest says his primary responsibility is to be an advocate for people in poverty and in danger. >> ( translated ): every migrant is a potential kidnapping victim, and the criminals extort up to $5,000 in order to set them free. >> reporter: with pressure and aid from the u.s. government, mexican authorities have been clamping down on central american migration and the number of people making it as far north as the u.s. border has dropped significantly, but they haven't stopped coming. >> reporter: these guys are really tired. they just got here early this morning. >> reporter: