More than 100 authors, poets and illustrators will gather on the National Mall for the National Book Festival this weekend.

The free annual event, sponsored by the Library of Congress and first-organized by former First Lady Laura Bush, will span two days for the first time this year.

“The National Book Festival exists because reading is intrinsically valuable, but we think it’s also a great deal of fun,” Jennifer Gavin, acting director of communications at the Library of Congress, said.

Part-time professor of creative writing Louis Bayard will sign copies of his mystery novel, “The School of Night,” and speak Sunday about writing and the publishing industry.

“There’s something really inspiring about seeing these thousands of readers milling across the Mall,” he said. “You go home thinking, ‘Okay, reading’s not quite dead. Not yet.’ ”