If you want to sell books during a pandemic, it turns out that one of the best places to do it is within easy reach of eggs, milk and diapers.

When the coronavirus forced the country into lockdown this spring, stores like Walmart and Target, which were labeled essential, remained open. So when anxious consumers were stocking up on beans and pasta, they were also grabbing workbooks, paperbacks and novels — and the book sales at those stores shot up.

“They sell groceries, they sell toilet paper, they sell everything people need during this time, and they’re open,” said Suzanne Herz, the publisher of Vintage/Anchor. “If you’re in there and you’re doing your big shop and you walk down the aisle and go, ‘Oh, we’re bored, and we need a book or a puzzle.’ There it is.”

Big box stores do not generally break out how much they sell of particular products, but people across the publishing industry say that sales increased at these stores significantly, with perhaps the greatest bump at Target. In some cases there, according to publishing executives, book sales tripled or quadrupled.

Dennis Abboud is the chief executive of ReaderLink, a book distributor that serves more than 80,000 retail stores, including big box and pharmacy chains. He said that in the first week of April, his company’s sales were 34 percent higher than the same period the year before.

“With the shelter in place, people were looking for things to do,” he said. “Workbooks, activity books and just general reading material saw a big increase.”

Some grocery chains and pharmacies saw an increase, too, even though books are far from the core of what they offer. A spokesman for Rite Aid said that since the beginning of March, the company has seen an increase in book sales generally, as well as in children’s books and puzzles. Meijer, a superstore chain based in the Midwest, also saw a “strong uptick” in book sales since the beginning of the pandemic, a spokesman said.

That company is in the process of expanding the book department in about 80 of its 253 stores, part of a plan that was in place before the pandemic. In addition to the advantage of just being open, stores like Target were able to step in when Amazon pulled back on delivering some products, like books and toys, so it could prioritize in-demand household goods and medical supplies.

Among the big box chains, each has a somewhat different bookselling approach. Walmart offers a lot of commercial fiction, books on topics like self-help and weight loss, as well as children’s books. Much of Target’s selection is aimed at female readers. Costco sells many classics, like “The Wizard of Oz” and Jane Austen, along with children’s workbooks.

But all the stores tend to stay in the same general neighborhood, selling books that are highly commercial. And they are a dominant force in commercial fiction. Mr. Abboud said that for some of the biggest authors in that category, as much as 75 percent of their volume flows through his company.

Even in normal times, getting a book on the shelves of a Target or a Walmart is a coup. As with anything they buy, when one of those chains stocks a title, they buy a lot of copies — as many as 30,000, a significant amount in an industry where a 50,000-book printing is considered a big bet.

At Costco, a big best seller might sell more than 100,000 copies. There, books are chosen by Pennie Clark Ianniciello, a longtime buyer who every month anoints one of her favorites as a “Pennie’s Pick,” a distinction that can substantially boost sales.

“The Seven or Eight Deaths of Stella Fortuna,” a novel by Juliet Grames, has sold almost 15,000 hardcover copies since it was published in May 2019, according to NPD BookScan. The paperback, however, was a Pennie’s Pick, and has sold more than 18,000 copies since it was published less than three months ago.

“If it hadn’t been a Pennie’s Pick, it would have been problematic because other brick and mortar bookstores were closed,” said Sarah Burnes, Ms. Grames’s literary agent. “Because it was a Pennie’s Pick, it sold thousands of copies.”

Walmart also saw its book sales jump.

“Covid-19 and the government stimulus checks have increased the demand for books in a big way, particularly on the adult books side,” Leigh Stidham, a Walmart spokeswoman, said in an email. “The fiction genre is strong despite some new title releases being pushed back to later in the year. Also, educational book sales have increased significantly since day cares and schools have been shut down.”

The question for publishers is whether this bump will continue. Have buyers been reconditioned to pick up books in different places, or will they go back to their old habits when running errands feels less fraught? Mr. Abboud of ReaderLink said he expects sales to fall, but not to previous levels. In the meantime, there are those who are starting to venture back out.

Carmina Ortiz went to the Target store in Edgewater, N.J., with her son Max, 8, last month to make a return. While they were there, they went to the young reader section, because the summer stretching out ahead of them is going to be a long one.

“I want him to read another series,” she said. “I’ve got to be the event coordinator, or it’s going to be all TV and video games.”

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