The OverDrive Digital Bookmobile will visit the Appoquinimink Community Library on Wednesday -- its first of three stops in the First State next week -- to promote the e-books and digital audio books available at Delaware public libraries.

One of the largest bookmobiles in the country will pull into Middletown's Appoquinimink Public Library on Wednesday.

Yet, this 74-foot-long, 18-wheeler won't contain any actual books.

That's because the OverDrive Digital Bookmobile is dedicated exclusively to promoting the electronic books and digital audio books available for download through most public libraries, including those in Delaware.

"We launched the Digital Bookmobile in 2008 and it's been travelling the country ever since, creating community events that help spread the word about e-book lending," said David Burleigh, a spokesman for OverDrive, the Ohio-based company that handles electronic book downloads for the Delaware Library Catalog, as well as 220,000 other libraries and schools throughout the country.

The tractor-trailer is equipped with five separate rooms where guests will be able to browse and sample the Delaware Library Digital Catalog, watch downloadable video content, as well as try out the latest electronic reading devices from Apple and Android phones and tablets to Nooks

and Kindles.

It's those devices that have helped to power the exponential growth in the popularity of e-books and digital audio books since the state library system first began offering them about 18 months ago, according to Bob Wetherall, the e-book administrator for the Delaware Division of Libraries.

In 2012, the state's catalog of 15,000 downloadable e-books and digital audio books had a circulation of 130,000, he said. This year, the library system hit that number by Labor Day – a date that also set the single-day record for digital circulation at more than 700 check outs.

"I think we're seeing the beginnings of a revolution that will continue to grow substantially over the years," Wetherall said. "When we began, most of the downloads were being done directly to computers. Now they're being downloaded more to smart phones and tablets, and as those items become more commonplace, the market for these e-books and audio books is only going to escalate."

Currently, e-books and audio books account for slightly less than 5 percent of the state libraries' total circulation. But State Librarian Annie Norman said that number is misleading considering the volume of physical materials available.

"We have 2.5 million print and other physical items that can be checked out of the state's 32 public libraries, so considering digital content is only a fraction of that, the circulation is actually quite impressive," she said. "If the digital catalog were its own library, it would be the 13th busiest library in the state right now."

To use the service, any patron with a library card can access the digital catalog through their local library's website or by going directly to

From there patrons can browse the available titles or search for their favorites before downloading up to four items at a time simply by entering their library card number.

Titles can be checked out for up to three weeks, after which the file will automatically disappear from the patron's device, completely eliminating the potential for late fees.

But while the "books" are digital, they're still treated in much the same way as printed material in that there is a limited supply of each title. Once that limit is reached, patrons will have to add their name to a waiting list until the title becomes available.

Beth-Ann Ryan, the deputy director of the state library division, said those limits are imposed by the publishing companies that sell the books.

Simply adding more copies also becomes an expensive proposition, because e-books and digital audio books are priced considerably higher than their print and CD counterparts, she said.

"Initially, the big six publishers raised the prices because they were afraid they were going to lose their market, and it's still a little like the Wild West as they try to figure out how they're going to make money," she said. "Harper Collins, for instance, is pricing its e-editions at a comparative level to its print editions, but after 26 uses the file disappears and you have to buy them again."

Norman said she's excited to have OverDrive's Bookmobile visit Delaware's three counties next week, starting with its stop at the Appoquinimink Public Library at 651 N. Broad St. from 1 p.m. to 7 p.m. on Wednesday.

The bookmobile will then head to Dover Public Library on Thursday, followed by a two-day stand at the Georgetown Public Library on Friday and Saturday.