In 1928, at the urging of Librarian of Congress Herbert Putnam, Congress authorized the purchase of land directly east of the Library's Main Building for the construction of an Annex Building. The bill was sponsored by Robert Luce, chairman of the House Committee on the Library. On June 13, 1930, $6,500,00 was appropriated for the building's construction, for a tunnel connecting it to the Main Building, and for changes in the east front of the Main Building, including the construction of a Rare Book Room. An additional appropriation approved on June 6, 1935, brought the total authorization to $8,226,457.
The simple classical structure was intended as a functional and efficient bookstack "encircled with work spaces." David Lynn, the Architect of the Capitol, commissioned the Washington architectural firm of Pierson & Wilson to design the building, with Alexander Buel Trowbridge as consulting architect. The contract stipulated completion by June 24, 1938, but the building was not ready for occupancy until December 2, 1938. The move of the Card Division started on December 12, and it opened its doors to the public in the new building on January 3, 1939. The building is five stories in height above ground, with the fifth story set back 35 feet. It contains 180 miles of shelving (compared to 104 miles in the Jefferson Building) and can hold ten million volumes. There are 12 tiers of stacks, extending from the cellar to the fourth floor. Each tier provides about 13 acres of shelf space.