For years the availability of free e-books from libraries was something of an underground secret.
But Amazon significantly increased the potential visibility of library e-books on Wednesday when it opened up its popular Kindle device to these books for the first time.
"Libraries are a critical part of our communities," Jay Marine, director of Kindle at Amazon, said in a statement. "And we're excited to be making Kindle books available at more than 1 1 ,000 local libraries around the country."
The introduction of the Kindle, the biggest-selling e-reader, opens up library e-books to a wider audience, heightening the fears of publishers that many customers will turn to libraries for reading material. If that happens, e-book buyers could become e-book borrowers, leading to a potentially damaging loss of revenue for an industry grappling with a profound shift in consumer reading habits.
Library e-books are already available on Barnes & Noble's Nook, the Sony Reader, smartphones, laptops, and other devices, but never on the Kindle, whose users had long complained they were left out.
"We do get asked the question frequently: 'Can I use my Kindle to download your e-books?'" said John F. Szabo, director of the Atlanta-Fulton Public Library System. "And the answer has been no."
The move by Amazon "is a big deal and it's a big step forward in public libraries being much more central in the whole e-book growth," said Steve Potash, the chief executive of OverDrive, a large provider of e-books to public libraries and schools. Connecting libraries with the Kindle, the most successful device and the largest e-book bookseller in the business, "is going to bring millions of readers to the public library," he said.
The publishing industry has been reluctant to criticize libraries and their e-book systems because of the cherished position libraries hold in communities. But some publishing executives said privately that they found the development troubling and were concerned it might lead to further unraveling of the traditional sales model.
As e-books have taken off with readers, libraries have been building their e-book collections to meet demand, successfully persuading many publishers to sell their titles to libraries in e-book format.
Christopher Platt, the director of collections and circulating operations at the New York Public Library, said that to meet demand from Kindle users, the library has already moved more money into the e-book budget and changed its default lending period for e-books from three weeks to two weeks.
"This is massive for libraries," Mr. Platt said. "It opens up another avenue of access to the collections that we already have. …