If one thing has seemed to unite Americans during the coronavirus pandemic, it’s spring cleaning. With stay-at-home orders in effect, a long-delayed clearing-out of basements, closets, back bedrooms and desk drawers has become a popular way to pass the time.

One result is that America's thrift stores (known as "recycle shops" in Japan) are informally reporting unprecedented volumes of donations. And that's creating a problem that goes far beyond finding a loving home for your old sweaters.

The secondhand industry is more important than most Americans realize. Largely out of sight, it employs tens of thousands of people and generates at least $18 billion in annual revenue. It keeps an enormous amount of used stuff out of landfills, and contributes billions each year to social-service and job-training programs that are crucial to communities nationwide. Those services are more important than ever in a pandemic. But to sustain them, Americans will have to take more care in donating their used stuff.