NASHVILLE (AP) - One of the book industry's largest print-on-demand operations has expanded to keep up with orders.

The Nashville-based Ingram Content Group's Lightning Source division opened three new facilities last month - two in the U.S., and one in Germany.

Print-on-demand books are a bright spot for the traditional book industry, which has slumped as e-readers increase. According to research for IT Strategies, around a billion pages are being printed on demand each month - driven by sales from Amazon.

Larry Brewster, who helped found Lightning Source, tells WPLN (http://bit.ly/HuOTDU) that the company can print a book and ship it out within 24 hours of getting an order.

"These machines, when we started out (in 1998), would print maybe 500 or 600 pages a minute," Brewster says. "Now they're printing 2,500 pages a minute."

At the company's Tennessee location, rolls of paper zipped through printers recently, then the pa ges were collated and the edges smoothed. It's only after the covers are placed on them that it becomes clear that they are different books coming off the printer at the same time.

Technology has improved so much that it is hard to tell the books didn't come from a tradition press, said Bob Edington, a vice president at Nashville-based Thomas Nelson Publishers.

"There's a difference, but it's really hard to discern," he said, adding that the publisher is moving more titles into the database at Lightning Source.

"With online and digital storage, there is infinite shelf space," he says. "So if it's available and someone can find it, it could be very obscure, but someone will probably order it."

It costs more to print one copy at a time, but he says money can also be lost by printing books that don't sell.

Ingram Content Group CEO Skip Prichard says the company can print books not just for publishers when there is a spike in demand or for companies like Amazon, but for individuals.

"There are times when you might want a printed copy. And you could press the button on your device and we could make that book for you and have it at your house the next day," he says. "We're positioned to do that."