UNDOCUMENTED migrants are rushing to Mexico's border with Arizona, encouraged by the prospect of a guest-worker programme in the United States and anticipating a toughening of border security that would make a dangerous journey even more perilous.
Detentions by the US border patrol in south-central Arizona, the busiest migrant-smuggling area, are up by more than 26 per cent since 1 October - 105,803, compared with 78,024 for the same period last year. Along the entire US- Mexico border, arrests have risen by 9 per cent.
Many migrants say they are being encouraged by relatives in the US, who are betting on the approval of a bill in Congress that would legalise some of the 11 million undocumented migrants in America.
Francisco Ramirez, 30, recently passed through Sasabe, a one-road town on the Arizona border that is a magnet for crossers, with dreams of heading to Minnesota, where two of his brothers milk cows on a ranch. "My brothers said there is plenty of work there and that it looks like they will start giving [work] permits," he said.
Maria Valencia, a spokeswoman for US Customs and Border Protection, said more detentions do not necessarily mean there are more people crossing. She said an increased number of border patrol agents has meant a greater proportion are getting picked up. "We've sent more technology and agents there, and I think that's had an impact," she said.
But Francisco Loureiro, who has managed a migrant shelter for 24 years in the nearby town of Nogales, said many more migrants are heading north. In March, an average of 2,000 stayed at the shelter - 500 more than in March 2005.
Mr Loureiro said he saw a similar spike in illegal migration in 1986, when the US approved legislation allowing 2.6 million undocumented migrants to get US citizenship.
"Every time there is talk of legalising migrants, people get their hopes up," he said.