BETHLEHEM, Pa. — Ellen Gaugler remembers driving her father to the Bethlehem Steel mill, where he spent his working years hauling beams off the assembly line and onto rail cars.

When the Pennsylvania plant shut down about two decades ago, Gaugler thought it was the last time she or anyone in Bethlehem would come to its gates to find a job that paid a decent wage for a physical day of work.

But she saw an ad in the paper last year for a position at a local warehouse that changed her mind. She’d never heard of Zulily, the online retailer doing the hiring, but she knew the address: It was on the old mill site, steps from where her father worked.

“When I came for the interviews I looked up and said, ‘Oh, my God, I feel like I am at home,’” Gaugler said. She got the job.

As shopping has shifted from conventional stores to online marketplaces, many retail workers have been left in the cold, but Gaugler is coming out ahead. Sellers like Zulily, Amazon and Walmart are competing to get goods to the buyer’s doorstep as quickly as possible, giving rise to a constellation of vast warehouses that have fueled a boom for workers without college degrees and breathed new life into pockets of the country that had fallen economically behind.

Warehouses have produced hundreds of thousands of jobs since the recovery began in 2010, adding workers at four times the rate of overall job growth. A significant chunk of that growth has occurred outside large metropolitan areas, in counties that had relatively little of the picking-and-packing work until recently.

“We are at the very beginning of a rather large transformation, and the humble warehouse is the leading edge of this,” said Michael Mandel, chief economic strategist at the Progressive Policy Institute in Washington. “These fulfillment center jobs are not being created in the tech hubs that were growing before. We’ve broadened the winner’s circle.”

The hubs of this network are far-flung. In Bullitt County, Kentucky, south of Louisville, warehouse employment surged to 6,000 in 2017 from 1,200 in 2010, according to the Labor Department. In Kenosha, Wisconsin, once a manufacturing hub whose auto plants turned out Nash Ramblers and Plymouth Horizons, warehouse jobs grew to 6,200 from 250 in the same period.

Those places have the advantage of being surrounded by highways and rail lines that lead to some of the nation’s largest cities. They also have an abundance of cheap land and labor, two assets that have become increasingly vital to companies selling online.

The same calculus has made a warehouse mecca out of the land that houses the carcass of Bethlehem Steel, giving natives like Gaugler a sense that their hometown may be thriving.

Gaugler, 54, earns $13.50 an hour putting together shipments at the Zulily warehouse, where employees tend to refer to their end customer as “Mom.” She works 10-hour shifts from Wednesday through Saturday, and puts in for overtime whenever she can.

“I like to get those orders out to Mom,” she said. The work is physically demanding, she said, but it’s straightforward. She gets a list of items to pull from shelves every morning — toys, glassware, baby clothes — and works her way to the bottom as quickly as possible. She’s gotten two raises, of 25 cents each, over the past year.

There are people in town who are nostalgic for the time when the mill filled the sky with black smoke and the furnaces churned all day. Not Gaugler. “These are secure jobs,” she said. “With the steel, you didn’t know if you would have a job the next day.”

Her father may have had a better deal at the mill — he got 13 weeks of vacation and “didn’t have to worry about bills every so often,” Gaugler said. But she only has an associate’s degree, and said this job pays better than most of her alternatives. It also comes with health insurance, paid time off and a 401(k) retirement plan.