Electronic books exploded last Christmas, and with the gadgets on which to read them getting more affordable and selling briskly this year, libraries are preparing for more readers looking to borrow books in digital form.

Last year, the computer system that supports e-books for Wisconsin libraries crashed a couple of days after Christmas as a crush of users tried to download e-books.

“Last year, we were caught a little bit unaware that there was going to be such a huge demand with the e-readers,” said Mary Knapp, a member of the Wisconsin Public Library Consortium, a nonprofit, statewide cooperative that helps library systems share resources. “This year we are hoping we’re going to be a little bit more on board.”

Library users can check out e-books for free and have three to 14 days to read them before they disappear from the e-reader.

The Madison Public Library has seen an increase in e-book checkouts this month, said Tana Elias, Web resources coordinator for the Madison Public Library. She expects it to continue through January as the next round of e-readers comes out and people learn to use their holiday gifts.

“Last year we saw a really big increase in December and January around the holidays, when everybody gets an e-reader or a smartphone and wants to try it out,” Elias said.

And there are bound to be more e-book readers under Christmas trees this year.

Amazon this month announced it sold more than 1 million of its Kindle devices in three consecutive weeks starting at Thanksgiving.

Statewide e-book checkouts went from 30,099 last year to 188,750 through November this year. When digital audiobook checkouts are added, the figures increase to 273,587 last year and 440,164 through November of this year. There was a bump in e-book lending in September after Amazon’s library opened up to Wisconsin’s 17 library systems.

The number of checkouts from people who live in Madison — including both e-books and downloadable audiobooks — was 20,171 last year and 32,187 through November this year.

While e-book borrowing is growing rapidly, it still accounts for only about 1 percent of the 3.7 million items local libraries circulated this year, Elias said.

The South Central Library System offers 7,075 e-book titles, with multiple copies of popular titles, the same way libraries buy multiple copies of popular print books.

“We started this project in 2006, and the growth in e-books over the last two years has been phenomenal, particularly with popular materials,” said Stef Morrill, director of Wisconsin Library Services, which is the project manager for the Wisconsin Public Library Consortium.

The consortium raised $1 million to buy digital materials in 2012, or 50 times what it spent in 2010. The majority of the money — $700,000 — came from member library systems; the other $300,000 was federal money, Morrill said.

Knapp, the consortium’s representative from the South Central Library System, helps select what titles the consortium will buy.

When she joined the committee about six years ago, it was almost exclusively ordering downloadable audiobooks, but purchases are now about 75 percent e-books, Knapp said.

It’s caught on because of the proliferation of not only e-readers, but also smartphones, iPads and other tablets, she said. “The fact that everyone can read books mobilely on devices, that is really where the future is.”

— The Associated Press contributed to this report.