Dwayne Wilson, 25, gets up every day at 4:30 a.m. to see whether he’s going to be needed as a forklift driver at the warehouse where he works in Wilmington, California, a neighborhood in the Los Angeles harbor area. Sometimes he gets a call telling him not to come in. Sometimes he goes in to find out that he’s not needed that day. On average, he only works three eight-hour days per week at $15 per hour.

The products that Wilson moves are destined for Amazon customers, but Wilson doesn’t work directly for the ecommerce giant. He works for California Cartage, a logistics company that has a contract to unpack shipping containers full of Amazon goods. Wilson says that the majority of the cargo moving through his warehouse is headed straight to an Amazon fulfillment facility.

The national unemployment rate hit 3.9 percent in April, the lowest since 2000, and companies across the country are complaining about the difficulty of finding workers. Yet Amazon has been able to staff its warehouses with workers who often earn little more than the local minimum wage. Many of them are contingent workers like Wilson, who get none of the stability and benefits that come with working for one of the country’s largest companies.

Amazon has been able to keep finding workers for its warehouses in part by tapping into areas where the recovery has been weak in order to find low-wage labor. New Jersey and California contain two of the largest numbers of Amazon fulfillment facilities in the U.S. In 2012, Amazon opened a warehouse in San Bernardino, California, a city about 70 miles east of Wilmington. San Bernardino had a per capita income of $14,922 according to latest American Community Survey in 2016, less than half the ACS’s current national income figure of $29,892. It didn’t recover to the number of jobs it lost in the recession until 2015 according to the Bureau of Labor Statistics.

The 2016 per-capita income of Carteret, New Jersey, another port city where Amazon opened a warehouse, is $24,926. On the whole, New Jersey’s recovery has been slower than California’s. It didn’t gain back the number of the jobs it had before the recession until 2016.

Wilson left a better-paying job in the warehouse of an animal pharmaceutical manufacturer in Omaha, Nebraska, to move in with his mother who was living on disability in Long Beach and needed his support. In California, they live together in a two-bedroom apartment for $1,400 per month. He initially began working at California Cartage because it was the only job he could get with his background in warehouse work.

Wilson’s situation might improve somewhat if he got a job with Amazon directly. But he faces long odds.

Sheheryar Kaoosji, an organizer at Warehouse Workers for Justice, an Inland Empire-based worker center, said that the demand for Amazon jobs in the area is so high, that is often a challenge for workers who are brought on a part-time basis to secure a regular full-time position. Those part-timers are often not told what time their shift begins until two hours before they are expected to show up.

“Those workers have to hustle to try to take every opportunity there given,” Kaoosji said. “If they pass something up. If they say, hey, I can’t make it this day, they’re much less likely to actually get that permanent position.”

Even when workers do get hired by Amazon, those jobs don’t necessarily last.

“Often we have folks who stick around after the Christmas rush, and they get laid off because Amazon–especially compared to a lot of companies–they have a really, really exaggerated kind of seasonal hiring,” said Kaoosji.

Wilson’s job is characteristic of many workers in the lowest rung of the logistics industry, which is increasingly being propelled directly or indirectly by Amazon. Both in Amazon facilities, and even more so in warehousing centers that handle Amazon freight, a large part of the workforce is often part-time or contingently employed through staffing agencies.

Northern New Jersey exurbs like Newark and New Brunswick are logistics hubs with a high concentration of “perma-temp” positions–where a temp agency connects workers to the same job at warehouse on a consistent basis. Carmen Martino, a labor studies professor at Rutgers, said that it’s common for temp agencies to pop up in neighborhoods with a high concentration of immigrant workers where the per-capita income is often low.

“Actually some years back, we mapped wherever the staffing agencies were located in proximity to where the workers lived,” Martino said. “And you can see in places like New Brunswick where the agencies were like a picket fence, right around the highest concentration of immigrant workers.”

Martino said it is cheaper for the warehouse to use temp agencies because they don’t have the responsibilities of injured workers or state and federal taxes on employees. It’s also more efficient for the temp agencies because they have to spend less time on training. Meanwhile, workers like Wilson, stuck under these conditions, have no benefits and unstable hours.

A Timeline of Amazon’s warehouse openings in California and New Jersey: