At first, experts waved off concerns about shortages. A Wall Street Journal editorial on March 22 declared, “There is one fear we can alleviate: the idea that America is running out of toilet paper.” But much of America did, in fact, run out.

By March 23, toilet paper was out of stock at 70% of U.S. grocery stores (including online sellers). “When everybody forward-buys, then you do create a shortage. Perception becomes reality,” says Pete Guarraia, who heads consultancy Bain & Company’s global supply-chain practice.

Toilet paper machines ran at 99.8% of capacity in March, according to Fastmarkets RISI, up from their normal 92%. Even so, overall U.S. production increased only 8%, to some 700,000 tons for the month. “This pandemic has revealed the limits of lean supply-chain management,” says Guarraia.