WASHINGTON — James Billington, the librarian of Congress who has led the world's largest library for nearly three decades and brought it into the digital age, announced Wednesday that he will step down at year's end.

The Library of Congress said Billington, 86, will retire on Jan. 1. He notified President Barack Obama of his plans, and the post will be filled by a presidential nomination with Senate confirmation.

Billington was just the 13th librarian since 1800. The library is the nation's oldest federal cultural institution. It was formed largely based on Thomas Jefferson's collection of books to begin building a national library. It now holds a vast collection of research materials, historical resources and cultural treasures.

"Leading this great institution alongside all of you for nearly three decades has been the honor and joy of my 42 years of public service in Washington, D.C.," Billington told the library's staff in a video announcement.

Since Billington joined the library in 1987, the collection has nearly doubled in size to 160 million items. It includes the personal manuscripts of Rosa Parks, Irving Berlin, Jackie Robinson, Steven Sondheim and others. The library also operates as a nonpartisan research organization for Congress and runs the nation's Copyright Office.

Billington is credited with leading the library into the digital age, making research materials and legislative databases available online. The library also built a massive audio-visual conservation center in a Virginia bunker to preserve the nation's great movies and sound recordings. Billington also initiated lifetime achievement awards in music and writing and created the National Book Festival with former first lady Laura Bush.

Before he joined the library, Billington graduated from Princeton and Oxford universities and taught history at Harvard and Princeton. He was director of the Woodrow Wilson International Center for Scholars when he was nominated by President Ronald Reagan to lead the Library of Congress. He is an expert on Russian history and accompanied the Reagans to the Soviet Summit in Moscow in 1988.

Senate Majority Leader Mitch McConnell lauded Billington's long tenure.

"Congress is grateful to have had an institution like Dr. Billington in its service for nearly three decades," he said.

While the library has been praised for its pioneering Internet work in making government information accessible and creating the World Digital Library, Billington also has been criticized for not keeping up with advances in technology.

A Government Accountability Office report this year found persisting failures in the library's management of its computer systems and cited Billington's failure to hire a permanent chief information officer.

"The library does not have the leadership needed to address these IT management weaknesses," the GAO said.

In a written statement Wednesday, Billington said he has never had more faith in the library's leadership and staff.

"I am confident that they will continue to innovate, adapt and improve on the work we have undertaken," Billington said.

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