C-SPAN is gearing up for wall-to-wall coverage of the 11th annual National Book Festival.

Each year, the BookTV section of C-SPAN broadcasts from the festival’s history/biography tent. The festival has expanded to two days this year (Sept. 24-25) and C-SPAN will have live coverage of both days.

C-SPAN has added something new this year, said host Peter Slen. The network will hold live on-stage audience/viewer chats with the authors delivering the concluding talks each day. On Saturday, Slen will have a discussion with Pulitzer Prize-winning journalist Isabel Wilkerson, author of “The Warmth of Other Suns,” and on Sunday he will talk with David McCullough, the two-time Pulitzer Prize winner and author of “The Greater Journey: Americans in Paris.” The Q&As will last 45 minutes, Slen said, and will involve questions from the audience and from viewers via phone, e-mail or twitter.

James H. Billington, the librarian of Congress, will launch the festival and its coverage on Saturday at 9:50 a.m. and 10 minutes later Washington Post columnist Eugene Robinson will be on camera discussing his new book “Disintegration: The Splintering of Black America.”

Throughout the day, Slen and fellow host Robb Harleston will interview writers.

In other book festival news, Barnes & Noble is replacing Borders as the event’s primary retailer.