Crossing Continents

Each year, thousands of illegal migrants try to enter the United States via a treacherous journey across the Arizona desert. Some succeed, while others are captured by US border patrols and are immediately deported - but not everyone is so fortunate. A growing number simply drop dead from exhaustion.The Missing Migrant Project works on identifying the deceased, piecing together clues found in the personal effects collected alongside the decomposed bodies found in the desert.In this programme, the BBC's Mexico correspondent Will Grant travels to Tucson, Arizona to meet project co-founder Robin Reineke to learn of the challenges facing her office in the small southwestern city of Tucson - which has the third-highest number of unidentified bodies in the United States, after New York and Los Angeles.Migrant rights groups say the vast expansion of the US Border Patrol has exacerbated the problem because the heightened policing of the border along traditional urban crossing points has forced clandestine border cros