Junk mail and discarded delivery boxes have turned into a hot commodity as the paper industry uses them as a substitute for recycled office paper, which became scarce as people work from home.

That is a sharp turnaround from two years ago, when the market for recycled catalogs, boxes and newspapers collapsed after China toughened its standards for waste paper imports.

Now, U.S. paper and cardboard mills are figuring out how to turn that trash into new toilet paper, coffee cups, paper towels and cardboard boxes. And they have more material to work with as people order more food and packages to their homes during the coronavirus.