Standing in the early morning darkness just 50m inside the US, Roberto Camacho is doing his best to ward off the cold. Dressed in a black bomber jacket with a baseball cap pulled low over his brow, he shuffles from foot to foot as he waits for a lift to work.
After 15 years working in the fields of California for American farmers, Mr Camacho has found a new life: two months ago he started working at the Golden Acorn Casino.
"It pays better," he says. "In the fields you work all hours, it's cold and hard and you don't get more than US$7 an hour. With this job I have regular hours, I know when I'm going to work and I know what I'm going to earn."
Mr Camacho is not unique. Agricultural laborers, almost exclusively Latinos and at least two-thirds of them undocumented, are moving into more stable, less harsh employment.
The migration from agriculture is taking its toll on one of the largest industries in the US, and particularly on California's $US32 billion a year sector. Faced with an exodus of labor to the construction industry as well as to the leisure and retail sectors, farmers are struggling to get their crops in. Ten percent of the cauliflower and broccoli harvest has been left to rot this year, and some estimates put the likely loss of the winter harvest as high as 50 percent.
Each morning at 4am workers like Camacho file through the border at the Mexican town of Mexicali to enter the US at Calexico.
There they are met by labour contractors who engage them for the day and ferry them directly to the fields in rattling old school buses.
Tightened border security is providing further complications. "This year is the worst," says Gilberto Lopez, a contractor waiting for his crews in the early morning. "They do a lot of checks, so the crossing's very slow. It can take an hour, hour and a half to cross."
Mr Lopez -- known to admirers and detractors as The Dog -- has been working in the Imperial Valley around Calexico for 39 years. Each day he hires 600 to 800 workers, but this year he's been unable to meet the farmers' demands. "There's lots of work and very few people," he says. "We never make up our teams. You could pay them US$10 an hour and it wouldn't make any difference." Most of the workers are paid US$7.25 an hour, above the minimum wage of US$6.75.
Around him, hundreds of people mill about, waiting for the ancient buses to leave for the fields. But there is a delay. A frost means the lettuce pickers cannot start until the temperature has risen. The people who bear the brunt of this are the day workers.
Rather than being paid from the time they are contracted, they are paid from the time they arrive at the fields.
"Some people say they should pay as soon as you get on the bus at 4.30am," says Claudia Magana, a team forewoman, as she sits on a half-full bus belching its way toward the nearby broccoli fields.
"But the contractors don't say anything." The bus stops at her house to pick up her 18-year-old son, a student who works four days a week in the fields to pay for his studies. He dreams of becoming an estate agent.