The National Book Festival in 2011 (Megan Buerger/The Washington Post ) The National Book Festival in 2011 (Megan Buerger/The Washington Post )

Continuing his extraordinary support for the Library of Congress, financier David M. Rubenstein has donated an additional $5 million to the National Book Festival.

The Library of Congress announced Rubenstein’s new gift this evening just before a gala at the Thomas Jefferson Building for more than 100 authors who have come to Washington for this weekend’s book festival.

Today’s announcement doubles a similar gift that Rubenstein made in 2010 when he made his first $5 million donation to the festival. And in 2011, he gave $300,000 more so that the festival could expand from a one-day event to a two-day event.

In 2012 Rubenstein, co-founder of the Washington-based private equity firm the Carlyle Group, also pledged $1.5 million over five years for the Library’s Literacy Awards, plus $250,000 for administrative support.

Jennifer Gavin, project manager for the Library of Congress National Book Festival, said that today’s $5 million gift will support the festival “for the next five years.”

The announcement of this substantial new infusion of funds came just hours after news broke that this weekend’s book festival may be the last one allowed on the National Mall. Gavin said, “We have become aware that the Park Service has plans to make changes on the Mall. What they are proposing would probably change the festival as it is currently presented.”

More than 200,000 people are expected to attend the festival tomorrow and Sunday.