LAST year, Christmas was the biggest single day for e-book sales by HarperCollins. And indications are that this year’s Christmas Day total will be even higher, given the extremely strong sales of e-readers like the Kindle and the Nook. Amazon announced on Dec. 15 that it had sold one million of its Kindles in each of the three previous weeks.

But we can also guess that the number of visitors to the e-book sections of public libraries’ Web sites is about to set a record, too.

And that is a source of great worry for publishers. In their eyes, borrowing an e-book from a library has been too easy. Worried that people will click to borrow an e-book from a library rather than click to buy it, almost all major publishers in the United States now block libraries’ access to the e-book form of either all of their titles or their most recently published ones.

Borrowing a printed book from the library imposes an inconvenience upon its patrons. “You have to walk or drive to the library, then walk or drive back to return it,” says Maja Thomas, a senior vice president of the Hachettte Book Group, in charge of its digital division.